退出后C程序崩溃

Question

i'm a total beginner at c Programming. So i might not know alot of stuffs. But could anyone tell me why is my code crashing as soon as it is done with the last line? could it be the arrays that i defined?

#include <stdio.h>
#include <stdlib.h>


void main()
{

unsigned int totSession, totStudent;
int x, y, i, j;
int *studID,*con,*k;
char (*name1)[40];
int *frequency;

printf("Enter number of consultation\n"); //input number of consultation
scanf("%d", &totSession);
printf("Enter number of students\n"); //input number of students
scanf("%d", &totStudent);

studID = (int *)malloc(totStudent * sizeof(int));
con = (int *)malloc(totStudent * sizeof(int)); 
name1 = (char *)malloc(totStudent * sizeof(char));
frequency = (int *)malloc(totStudent * sizeof(int));
k = (int *)malloc(totSession * sizeof(int));

for (x = 0; x < totStudent; ++x) //Entering each students details
{
    printf("Enter details of Student[%d]\n", x + 1);
    printf("Enter StudentID:");
    scanf("%d", &studID[x]);
    printf("Enter student's Full name:");
    scanf("%s", &name1[x]);
    printf("Which consultation to choose for student:");
    scanf("%d", &con[x]);
}

printf("%s%15s%40s\n", "Student ID", "Fullname", "Which consultation session to choose");

for (y = 0; y < totStudent; ++y) //print all student details
{
    printf("%-17d%-23s%d\n\n", studID[y],name1[y],con[y]);
}


for (i = 0; i <= totStudent; ++i) //set all arrays of frequency to 0
{
    frequency[i]=0;
    k[i] = 0;
}

for (i = 0; i < totStudent; ++i) //summarise consultation
{
    ++frequency[con[i]];
    k[i + 1] += (i+1);           //create constant for session number
}

if (totStudent > 1)
{
    int hold, hold1;
    for (i = 0; i < totSession; ++i) //sorting
    {
        for (j = 1; j <= (totSession - 1); ++j)
        {

            if (frequency[j] < frequency[j + 1])
            {
                hold = frequency[j];
                hold1 = k[j];
                frequency[j] = frequency[j + 1];
                k[j] = k[j + 1];
                frequency[j + 1] = hold;
                k[j + 1] = hold1;
            }
        }
    }
}
printf("%s%50s", "Consultation Session Number", "The number of students choose this session\n");

for (i = 1; i <= totSession; ++i)
{
    printf("%10d%40d\n",k[i], frequency[i]);
}
printf("The session to offer is: Session %d with %d (out of %d) students chosen.\n", k[1], frequency[1], totStudent);


getch();
}

any help would be appreciated!! have done free() at the end of the codes, but it doesnt work too..

Answer 1

If by "crashing" you mean it fails to compile the source with the following error:

/tmp/ccvGANfB.o: In function `main':
tmp.c:(.text+0x4d2): undefined reference to `getch'
collect2: error: ld returned 1 exit status

it's because you are trying to use a function (getch) that doesn't exists (to be fair it exists inside the curses library, but I highly doubt that's what you mean to use). You probably missplelled getchar().

In short, in the last line substitute

 getch();

with

 getchar();

PS: by "crashing" one usually refers to a run-time error (the program fails while executing ; your program does not compile, it throws a compile time error.