在 c 中使用 strsep 函数需要帮助

Question

int main(int argc, char *argv[])    
 {
    char *line, buffer[1024];
    char *token, *setValue, *pointer;


    FILE *fp = fopen("file", "r");
    if(fp == NULL)
    {
        printf("File was unable to be opened.\n");

    }

     fgets(buffer,1024,fp);  
      printf("%s\n", buffer);
     while(fgets(buffer,1024,fp) != NULL)
  {
    strcpy(token, strsep(&buffer, ","));
    printf("%s\n", token);
  }



 return 0;
 }

I'm having a bit of trouble understanding how strsep works.. I've looked up tutorials for it, but when I try different methods, it keeps just not being able to compile.. It'd be appreciated if someone helped me understand the syntax and the way it works. Thank you.

**EDIT: 'Buffer' contains "I,was,in,the,school"

****EDIT x2: I'm trying to parse a csv file, and using the basic 'Buffer' I created on my desktop as an example. I want to separate the different words by the respective comma.

Answer 1

regarding:

strcpy(token, strsep(&buffer, ","));

the variable token is ONLY a pointer, it has not been set to point to any memory that the application owns. Therefore, it will contain what ever trash was on the stack at the location of the variable.

The result is undefined behavior and it can lead to a seg fault event.

Suggest declare token as

char token[ 1024 ];

so it is large enough to hold a maximum length string (IE the length of buffer[]

as it the above wasn't bad enough:

the posted code is missing the statement: #include <string.h> so as to expose the prototype for the function strsep() so the compiler will make the assumption that the parameters and returned value are int rather than their actual types.

The posted code is also missing the statement: #include <stdio.h> so the parameter and return types for the functions: fopen() , fgets() , printf() and even the struct type for FILE are assumed to be int` rather than their actual types.