Question

I have difficulty using malloc and fscanf.
I just want to read a file and print out the result using
I got a segmentation fault error when I executed this code.
I am not sure what I have done wrong. I would be very grateful if someone points out a fix.
Here is my code:

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

int main(int argc, char* argv[]){
    char* buffer = (char*)malloc(*argv[1]); // Allocate memory 
    if(buffer=NULL) // if *argv[1] is not existed, exit the program    
        exit(1);

    int n = 0;
    FILE* fp=fopen("file.txt","r"); // Open the file
    do {
        buffer[n] =fscanf(fp,"%c",buffer); // read from file until it gets EOF
    } while(buffer[n] != EOF);
    fclose(fp); // Close the file

    printf("%s",buffer); // Print the stored string

    free(buffer); // Return the memory
    return 0;    
}

Answer 1

Got it. This:

if(buffer=NULL)

should be this:

if(buffer==NULL)

You’re setting buffer to NULL. I’m sure you can see what happens next.

More generally, this code is trying to do several things, and it’s full of bugs. You should have tested the different functions separately and worked out those bugs along the way.