经过一定程度的有意溢出和最高自动清除后，C语言中的多堆栈程序显示了错误的元素

Question

Here's the C program I'm working on right now, which should let users to handle up to 5 stacks at a go and it will autoremove the toppermost item before adding the user-specified number if the stack in question is full. However it's been plagued by a kraken in which after 3 or more distinct stacks are intentionally overflowed and thus triggering the autoremoval function, the "show all elements at all stacks" function would begin to display incorrect results instead.

Either I've missed something or a poltergeist kraken at play.

Source code:

#include <stdio.h>
#include <malloc.h>
#define MAX 4
int stack[MAX], topA = -1;
int stackb[MAX], topB = -1;
int stackc[MAX], topC = -1;
int stackd[MAX], topD = -1;
int stacke[MAX], topE = -1;

void pushA(int val)
{
    if (topA == MAX)
    {
        int vala = val;
        printf("\n Bin 0 full! Removing the toppest one and proceeds to add the specified item");
        val = 0;
        val = stack[topA];
        topA--;
        stack[topA + 1] = vala;
        topA++;
        vala = 0;
    }
    else
    {
        stack[topA + 1] = val;
        topA++;
    }
}

int popA()
{
    int val;
    if (topA == -1)
    {
        printf("\n Underflow");
    }
    else
    {
        val = stack[topA];
        topA--;
    }
    return val;
}

void display_stackA()
{
    int i;
    if (topA == -1)
        printf("\n Stack A is empty");
    else
    {
        for (i = topA; i >= 0; i--)
            printf("\t %d", stack[i]);
    }
}

void pushB(int val)
{
    if (topB == MAX)
    {
        int valb = val;
        printf("\n Bin 1 full! Removing the toppest one and proceeds to add the specified item");
        val = 0;
        val = stackb[topB];
        topB--;
        stackb[topB + 1] = valb;
        topB++;
        valb = 0;
    }
    else
    {
        stackb[topB + 1] = val;
        topB++;
    }
}

int popB()
{
    int val;
    if (topB == -1)
    {
        printf("\n Underflow");
    }
    else
    {
        val = stackb[topB];
        topB--;
    }
}

void display_stackB()
{
    int i;
    if (topB == -1)
        printf("\n Stack B is Empty");
    else
    {
        for (i = topB; i >= 0; i--)
            printf("\t %d", stackb[i]);
    }
}

void pushC(int val)
{
    if (topC == MAX)
    {
        int valc = val;
        printf("\n Bin 2 full! Removing the toppest one and proceeds to add the specified item");
        val = 0;
        val = stackc[topC];
        topC--;
        stackc[topC + 1] = valc;
        topC++;
        valc = 0;
    }
    else
    {
        stackc[topC + 1] = val;
        topC++;
    }
}

int popC()
{
    int val;
    if (topC == -1)
    {
        printf("\n Underflow");
    }
    else
    {
        val = stackc[topC];
        topC--;
    }
}

void display_stackC()
{
    int i;
    if (topC == -1)
        printf("\n Stack C is Empty");
    else
    {
        for (i = topC; i >= 0; i--)
            printf("\t %d", stackc[i]);
    }
}

void pushD(int val)
{
    if (topD == MAX)
    {
        int vald = val;
        printf("\n Bin 3 full! Removing the toppest one and proceeds to add the specified item");
        val = 0;
        val = stackd[topD];
        topD--;
        stackd[topD + 1] = vald;
        topD++;
        vald = 0;
    }
    else
    {
        stackd[topD + 1] = val;
        topD++;
    }
}

int popD()
{
    int val;
    if (topD == -1)
    {
        printf("\n Underflow");
    }
    else
    {
        val = stackd[topD];
        topD--;
    }
}

void display_stackD()
{
    int i;
    if (topD == -1)
        printf("\n Stack D is Empty");
    else
    {
        for (i = topD; i >= 0; i--)
            printf("\t %d", stackd[i]);
    }
}

void pushE(int val)
{
    if (topE == MAX)
    {
        int vale = val;
        printf("\n Bin 4 full! Removing the toppest one and proceeds to add the specified item");
        val = 0;
        val = stacke[topE];
        topE--;
        stacke[topE + 1] = vale;
        topE++;
        vale = 0;
    }
    else
    {
        stacke[topE + 1] = val;
        topE++;
    }
}

int popE()
{
    int val;
    if (topE == -1)
    {
        printf("\n Underflow");
    }
    else
    {
        val = stacke[topE];
        topE--;
    }
}

void display_stackE()
{
    int i;
    if (topE == -1)
        printf("\n Stack E is Empty");
    else
    {
        for (i = topE; i >= 0; i--)
            printf("\t %d", stacke[i]);
    }
}

int main()
{
    int option, options, val;
    val = 0;
    do
    {
        printf("\n -----Menu----- ");
        printf("\n 1. PUSH a element");
        printf("\n 2. POP a element");
        printf("\n 3. Display all items");
        printf("\n 4. Exit");
        printf("\n Enter your choice");
        scanf("%d", &option);
        if (option == 1)
        {
            printf("\n Select ID no (0-4)");
            scanf("%d", &options);
            printf("\n Enter the value to push on your selected id:");
            scanf("%d", &val);
            if (options == 0)
            {
                pushA(val);
            }
            if (options == 1)
            {
                pushB(val);
            }

            if (options == 2)
            {
                pushC(val);
            }

            if (options == 3)
            {
                pushD(val);
            }

            if (options == 4)
            {
                pushE(val);
            }
        }

        if (option == 2)
        {
            printf("\n Select ID no (0-4) to pop");
            scanf("%d", &options);
            if (options == 0)
            {
                printf("\n Toppest item popped from ID 0");
                popA();
            }

            if (options == 1)
            {
                printf("\n Toppest item popped from ID 1");
                popB();
            }

            if (options == 2)
            {
                printf("\n Toppest item popped from ID 2");
                popC();
            }

            if (options == 3)
            {
                printf("\n Toppest item popped from ID 3");
                popD();
            }

            if (options == 4)
            {
                printf("\n Toppest item popped from ID 4");
                popE();
            }
        }

        if (option == 3)
        {
            printf("\n The contents of ID 0 are :\n");
            display_stackA();
            printf("\n The contents of ID 1 are :\n");
            display_stackB();
            printf("\n The contents of ID 2 are :\n");
            display_stackC();
            printf("\n The contents of ID 3 are :\n");
            display_stackD();
            printf("\n The contents of ID 4 are :\n");
            display_stackE();
        }
    } while (option != 4);
    return 0;
}

Output:

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)0

 Enter the value to push on your selected id:1

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)0

 Enter the value to push on your selected id:2

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)0

 Enter the value to push on your selected id:3

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)0

 Enter the value to push on your selected id:4

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)0

 Enter the value to push on your selected id:5

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice3

 The contents of ID 0 are :
         5       4       3       2       1
 The contents of ID 1 are :

 Stack B is Empty
 The contents of ID 2 are :

 Stack C is Empty
 The contents of ID 3 are :

 Stack D is Empty
 The contents of ID 4 are :

 Stack E is Empty
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)0

 Enter the value to push on your selected id:6

 Bin 0 full! Removing the toppest one and proceeds to add the specified item
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice3

 The contents of ID 0 are :
         6       4       3       2       1
 The contents of ID 1 are :

 Stack B is Empty
 The contents of ID 2 are :

 Stack C is Empty
 The contents of ID 3 are :

 Stack D is Empty
 The contents of ID 4 are :

 Stack E is Empty
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)1

 Enter the value to push on your selected id:1

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)1

 Enter the value to push on your selected id:2

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)1

 Enter the value to push on your selected id:3

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)1

 Enter the value to push on your selected id:4

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)1

 Enter the value to push on your selected id:5

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)1

 Enter the value to push on your selected id:6

 Bin 1 full! Removing the toppest one and proceeds to add the specified item
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice3

 The contents of ID 0 are :
         6       4       3       2       1
 The contents of ID 1 are :
         6       4       3       2       1
 The contents of ID 2 are :

 Stack C is Empty
 The contents of ID 3 are :

 Stack D is Empty
 The contents of ID 4 are :

 Stack E is Empty
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)2

 Enter the value to push on your selected id:1

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice3

 The contents of ID 0 are :
         6       4       3       2       1
 The contents of ID 1 are :
         6       4       3       2       1
 The contents of ID 2 are :
         1
 The contents of ID 3 are :

 Stack D is Empty
 The contents of ID 4 are :

 Stack E is Empty
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)2

 Enter the value to push on your selected id:2

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)2

 Enter the value to push on your selected id:3

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice3

 The contents of ID 0 are :
         6       4       3       2       1
 The contents of ID 1 are :
         6       4       3       2       1
 The contents of ID 2 are :
         3       2       1
 The contents of ID 3 are :

 Stack D is Empty
 The contents of ID 4 are :

 Stack E is Empty
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)2

 Enter the value to push on your selected id:4

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)2

 Enter the value to push on your selected id:5

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)2

 Enter the value to push on your selected id:6

 Bin 2 full! Removing the toppest one and proceeds to add the specified item
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice3

 The contents of ID 0 are :
         6       4       3       2       1
 The contents of ID 1 are :
         6       4       3       2       6
 The contents of ID 2 are :
         6       4       3       2       1
 The contents of ID 3 are :

 Stack D is Empty
 The contents of ID 4 are :

 Stack E is Empty
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)3

 Enter the value to push on your selected id:1

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)3

 Enter the value to push on your selected id:2

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)3

 Enter the value to push on your selected id:3

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)3

 Enter the value to push on your selected id:4

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)3

 Enter the value to push on your selected id:5

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)3

 Enter the value to push on your selected id:6

 Bin 3 full! Removing the toppest one and proceeds to add the specified item
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice3

 The contents of ID 0 are :
         6       4       3       2       6
 The contents of ID 1 are :
         1       4       3       2       6
 The contents of ID 2 are :
         6       4       3       2       1
 The contents of ID 3 are :
         6       4       3       2       1
 The contents of ID 4 are :

 Stack E is Empty
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)4

 Enter the value to push on your selected id:1

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)4

 Enter the value to push on your selected id:2

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)4

 Enter the value to push on your selected id:3

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)4

 Enter the value to push on your selected id:4

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)4

 Enter the value to push on your selected id:5

 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice1

 Select ID no (0-4)4

 Enter the value to push on your selected id:6

 Bin 4 full! Removing the toppest one and proceeds to add the specified item
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice3

 The contents of ID 0 are :
         6       4       3       2       6
 The contents of ID 1 are :
         1       4       3       2       6
 The contents of ID 2 are :
         6       4       3       2       6
 The contents of ID 3 are :
         6       4       3       2       1
 The contents of ID 4 are :
         6       4       3       2       1
 -----Menu-----
 1. PUSH a element
 2. POP a element
 3. Display all items
 4. Exit
 Enter your choice

Answer 1

As Jonathan says, a table declared with a size of 4 elements can only use the indices of 0 to 3. It's my day of goodness, I give you a condensed version with functions common to 5 stacks. I have not tested completely, but it will do you a good exercise to understand it and correct it with the recommendations of Jonathan. This code can still be improved. Your turn !

#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include <assert.h>
#define STACK_QTY   5
#define MAX         4

int stack[STACK_QTY][MAX];
int top[STACK_QTY];

void push(int index, int val)
{
    assert(index < STACK_QTY);

    if(top[index] == (MAX - 1)) {
        printf("\n Bin %d full! Removing the toppest one and proceeds to add "
               "the specified item", index);
        stack[index][top[index]] = val;
    }
    else {
        stack[index][++top[index]] = val;
    }
}

int pop(int index)
{
    assert(index < STACK_QTY);

    int val = -1;

    if(top[index] == -1) {
        printf("\n Underflow");
    }
    else {
        val = stack[index][top[index]--];
    }

    return val;
}

void display_stack(int index)
{
    assert(index < STACK_QTY);

    int i;
    if(top[index] == -1) {
        printf("\n Stack %c is empty", index + 'A');
    }
    else {
        for(i = top[index]; i >= 0; i--) {
            printf("\t %d",stack[index][i]);
        }
    }
}

void option1(void)
{
    unsigned int index = -1;
    int value;

    printf("\n Select ID no (0-%d)", STACK_QTY - 1);
    scanf("%u",&index);
    if (index < STACK_QTY){
        printf("\n Enter the value to push on your selected id:");
        scanf("%u",&value);

        push(index, value);
    }
    else {
        printf("error");
    }
}

void option2(void)
{
    unsigned int index;

    printf("\n Select ID no (0-%d) to pop", STACK_QTY - 1);
    scanf("%u",&index);
    if (index < STACK_QTY){
        printf("\n Toppest item popped from ID %d", index);

        printf("\nvalue = %d\n", pop(index));
    }
    else {
        printf("error");
    }
}

void option3(void)
{
    int i;

    for (i = 0; i < STACK_QTY; ++i) {
        printf("\n The contents of ID %d are :\n", i);
        display_stack(i);
    }
}

int main()
{
    int option;

    for (int i = 0; i < STACK_QTY; ++i) {
        top[i] = -1;
    }

    do {
        printf("\n -----Menu----- ");
        printf("\n 1. PUSH a element");
        printf("\n 2. POP a element");
        printf("\n 3. Display all items");
        printf("\n 4. Exit");
        printf("\n Enter your choice");
        scanf("%d", &option);
        switch(option)  {
            case 1: option1(); break;
            case 2: option2(); break;
            case 3: option3(); break;
        }
    }
    while(option != 4);

    return 0;
}

Answer 2

Your stacks can only hold 4 items (because of #define MAX 4 and int stackN[MAX]; ) but you don't protect properly against overflow. For example, if you manipulate stack A and push 37, topA is 0; push 41 and topA is 1; push 43 and topA is 2; push 47 and topA is 3 (and the stack is full), but when you push 51, you don't hit the topA == MAX condition, so you overflow your stack — overwriting who knows what! (It might be one of the topN values; it might be part of another stack; neither is good, and neither is what you intended.)

I've got a web site for you — Stack Overflow !

The simplest fix is probably to change the semantics of topN so that it is initialized to 0 instead of -1 . You then have to adjust the edge conditions in all the functions.

You really need to avoid having so many functions (5 copies of each of 3 functions). That's a more major rewrite. You should also use a structure to describe each stack. You're excused if you've not learned structures yet (but then you should use an array of top values a 2D array for the stack data. That would make the fixes needed much easier; you'd have 1/5th as many places to edit systematically.