Simple array operation in C

Question

I have just completed a simple array operation in C. I have done the programming consisting of a number of functions all performing the insert operation at various locations. The main problem that I'm facing is that the control is not returning to main after I have performed the operation with a function . I can't find the reason. Just explain why is this happening and provide me with a proper solution. My code is like this:

//To insert an element into an already formed array
#include<stdio.h>
#include<stdlib.h>
int binsert(int[],int);
int minsert(int[],int,int);
int einsert(int[],int);
void print(int[],int);
void main()
{
    int a[100],i,j,l,loc;
    printf("Enter the length of the array\n");
    scanf("%d",&l);
    printf("Enter the numbers in the array\n");
    for(j=0;j<l;j++)
    {
        scanf("%d",&a[j]);
    }
    printf("Enter the following options for the operation\n1:insert at the     beginning\n2:insert at specific location\n3:insert at the end\n4:print the array\nAny other key to end the operation\n");
    scanf("%d",&i);
    do
    {   
        switch(i)
        {
             case 1:
                    l=binsert(a,l);
                    break;
             case 2:
                    printf("Enter the location at which you would want to insert(location starts from    1)\n");
                    scanf("%d",&loc);
                    l=minsert(a,loc,l);
                    break;
             case 3:
                    l=einsert(a,l);
                    break;
             case 4:
                    print(a,l);
                    break;
        }
     }while(i==1 || i==2 || i==3 || i==4);
     printf("Operation terminated\n");
     exit(0);
}

int binsert(int a[],int l)
{
    int i;
    for(i=l-1;i>=0;i--)
    {
        a[i+1]=a[i];
    }
    printf("Enter the number to insert\n");
    scanf("%d",&a[0]);
    return (l+1);
}

int minsert(int a[],int loc,int l)
{ 
    int i;
    for(i=l-1;i>=loc;i--)
    {
       a[i+1]=a[i];
    }
    printf("Enter the number to insert\n");
    scanf("%d",&a[loc]);
    return (l+1); 
}

int einsert(int a[],int l)
{
    printf("Enter the number to insert\n");
    scanf("%d",&a[l+1]);
    return (l+1);
}

void print(int a[],int l)
{
    int i;
    printf("The values in the array are as follows\n");
    for(i=0;i<l;i++)
    {
        printf("%d\n",a[i]);
    }
}

Answer 1

PROBLEM 1 :
you should have done :

    do
    {   
        printf("Enter the following options for the operation\n1:insert at the     beginning\n2:insert at specific location\n3:insert at the end\n4:print the array\nAny other key to end the operation\n");
        scanf("%d",&i);

        switch(i)
        {
            ....
        }
    }while(i==1 || i==2 || i==3 || i==4);

otherwise , i will always contain the same value ie among 1 , 2, 3, 4 , and while(i==1 || i==2 || i==3 || i==4); will always be true , and so same function will be called indefinitely.

PROBLEM 2 : have a check on l , so that it do not exceed 100 , size of your array .

Answer 2

What you think?

//To insert an element into an already formed array
#include<stdio.h>
#include<stdlib.h>
int binsert(int[],int);
int minsert(int[],int,int);
int einsert(int[],int);
void print(int[],int);
void main()
{
    int a[100],i,j,l,loc;
    for(i=0; i < 100; i++)
        a[i] = -1;
    printf("Enter the length of the array\n");
    scanf("%d%*c",&l);
    for(j=0; j<l; j++)
    {
        system("cls");
        printf("Enter the numbers in the array\n");
        for(i = 0; i < j; i++)
            printf("%d ", a[i]);
        scanf("%d%*c",&a[j]);
    }
    do
    {
        system("cls");
        printf("Array: ");
        for(j = 0; j < (sizeof(a)/sizeof(a[0])) && a[j] != -1; j++)
            printf("%d ", a[j]);
        printf("\n\n\nEnter the following options for the operation\n\n\t1:insert at the beginning\n\t2:insert at specific location\n\t3:insert at the end\n\t4:print the array\n\tAny other key to end the operation\n\nOption: ");
        scanf("%d%*c",&i);
        switch(i)
        {
        case 1:
            l=binsert(a,l);
            break;
        case 2:
            printf("Enter the location at which you would want to insert(location starts from 1)\n");
            scanf("%d",&loc);
            l=minsert(a,loc,l);
            break;
        case 3:
            l=einsert(a,l);
            break;
        case 4:
            print(a,l);
            break;
        }
    }
    while(i==1 || i==2 || i==3 || i==4);
    printf("\n\nOperation terminated\n");
    getchar();
    exit(0);
}

int binsert(int a[],int l)
{
    int i;
    for(i=l-1; i>=0; i--)
    {
        a[i+1]=a[i];
    }
    printf("\n\nEnter the number to insert\n");
    scanf("%d",&a[0]);
    return (l+1);
}

int minsert(int a[],int loc,int l)
{
    int i;
    for(i=l-1; i>=loc; i--)
    {
        a[i+1]=a[i];
    }
    printf("\n\nEnter the number to insert\n");
    scanf("%d",&a[loc]);
    return (l+1);
}

int einsert(int a[],int l)
{
    printf("\n\nEnter the number to insert\n");
    scanf("%d",&a[l+1]);
    return (l+1);
}

void print(int a[],int l)
{
    int i;
    printf("\n\nThe values in the array are as follows\n");
    for(i=0; i<l; i++)
    {
        printf("%d\n",a[i]);
    }
}

Answer 3

I think below line is causing problem

for(i=l-1;i>=0;i--)
{a[i+1]=a[i];
}

It's like when i becomes 0 it will execute and then i-- will cause it to be -1 and negative numbers are stored in 2's complement so it will be positive number and condition i>=0 is satisfied every time.

Hope this might help you

Thanks