Question

#include<stdlib.h>
#include<stdio.h>
#include<string.h>
//This program is a sorting application that reads a sequence of numbers from a file and prints them on the screen . The reading from the file here , is a call back function . 

typedef int (*CompFunc)(const char* , const char* );
typedef int (*ReadCheck)(char nullcheck);
int array[100];
//Let this function be done in the library itself . It doesn't care as to where the compare function and how is it implemented . Meaning suppose the function wants to do sort in ascending order or in descending order then the changes have to be done by the client code in the "COMPARE" function who will be implementing the lib code . 
void ReadFile(FILE *fp,ReadCheck rc)
{
    char a;
    char d[100];
    int count = 0,count1=0,k;
    a=fgetc(fp);

    while (1 !=(*rc)(a) ) 
    {   if(a==' ')
        {

        d[count1]='\0';
        array[count]=atoi(d);

        count=count+1;

        printf("%s \n",d);
        memset(d,'\0',100);
        count1=0;
        }
        else
        {

        d[count1]=a;
        count1=count1+1;


        }

        a=fgetc(fp);
    }

}
void Bubblesort(char* array , int size , int elem_size , CompFunc cf)
{   int i,j,k;
    int *temp;
    for( i=0;i < size ;i++)
    {
        for ( j=0;j < size -1 ; j++)
        {
            // make the callback to the comparision function
            if(1 == (*cf)(array+j*elem_size,array+ (j+1)*elem_size))
                {

    //interchanging of elements 
                    temp =  malloc(sizeof(char *) * elem_size);
                    memcpy(temp , array+j*elem_size,elem_size);
                    memcpy(array+j*elem_size,array+(j+1)*elem_size,elem_size);
                    memcpy(array + (j+1)*elem_size , temp , elem_size);
                    free(temp);
                }
        }
    }


}



//Let these functions be done at the client side 

int Compare(char* el1 , char* el2)
    {
        int element1 = *(int*)el1;
        int element2 = *(int*)el2;

        if(element1 < element2 )
            return -1;
        if(element1 > element2)
            return 1 ;
        return 0;
    }

int ReadChecked(char nullcheck)
    {
        if (nullcheck=='\n')
            return 1;
        else 
            return 0;
    }
int main()
{
    FILE *fp1;
    int k;
    fp1=fopen("readdata.txt","r");

    ReadFile(fp1,&ReadChecked);
printf("before sorting \n");
    for (k=0;k<6;k++)
    printf("%d \n",array[k]);

        Bubblesort((char*)array,5,sizeof(array[0]),&Compare);
    printf("after sorting \n");
    for (k=0;k<5;k++)
    printf("%d \n",array[k]);

return 0;
}

When I run this code I don’t get any error. Apart from few warnings, but when I run it in another system, the code crashes. May I know why?

Answer 1

fsc1.c: In function ‘ReadFile’:
fsc1.c:19: warning: passing argument 1 of ‘strcpy’ makes pointer from integer without a cast

You should be passing &array[count] as the first parameter, not array[count].

fsc1.c: In function ‘Bubblesort’:
fsc1.c:40: warning: passing argument 1 of ‘cf’ from incompatible pointer type
fsc1.c:40: warning: passing argument 2 of ‘cf’ from incompatible pointer type

I would call cf as (*cf)(&array[j], &array[j+1]), no need to worry about element size as compiler will take care of it.

fsc1.c:43: warning: incompatible implicit declaration of built-in function ‘malloc’
fsc1.c:47: warning: incompatible implicit declaration of built-in function ‘free’

You need to #include <stdlib.h>

fsc1.c: In function ‘main’:
fsc1.c:80: error: incompatible types in assignment

fp1 should be declared as a FILE *.

fsc1.c:82: warning: passing argument 1 of ‘Bubblesort’ from incompatible pointer type

Your array is a char array, whereas the first parameter of Bubblesort expecting an int *. I would change Bubblesort to take a char *.