Get a segment fault while reading a file

问题

I want to read the whole file content and print it out , but I get a segment fault , I can't find what's wrong with the code ...

#include <stdio.h>
#include <stdlib.h>
int main()
{
    FILE * file;
    long fsize;
    file = fopen("./input.txt","r");
    if(file != NULL){

        //get file size
        fseek(file,0,SEEK_END);
        fsize = ftell(file);
        rewind(file);

        // print
        char * file_content;
        fgets(file_content,fsize,file);
        puts(file_content);
    }
    else{
        printf("open failure\n");
    }
    fclose(file);

    return 0;
}

回答1:

The pointer you pass to fgets (file_content) is uninitialized. It should be pointing to a block of memory large enough to contain the specified number (fsize) of bytes. You can use malloc to allocate the memory.

char* file_content = (char*)malloc(fsize);

回答2:

char * file_content is just a pointer, you need to allocate memory to store the string.

char * file_content;
file_content = malloc(fsize);

回答3:

"..but I get a segment fault"

Obviously because you're attempting to write to an uninitialized file_content

Allocated memory for file_content before use

char * file_content =malloc(fsize);

来源：https://stackoverflow.com/questions/18701924/get-a-segment-fault-while-reading-a-file