如何修复将'char [16]'传递给'FILE *'类型的参数（又名'struct __sFILE *'）的不兼容指针类型[-Wincompatible-pointer-types]

Question

how to fix?

warning:

incompatible pointer
types passing 'char [16]' to parameter of type 'FILE *'
(aka 'struct __sFILE *') [-Wincompatible-pointer-types]
fread(buffer,1,512,data);
^~~~
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/
SDKs/MacOSX10.13.sdk/usr/include/stdio.h:247:90: note:
passing argument to parameter '__stream' here
...__ptr, size_t __size, size_t __nitems, FILE * __restrict __stream);
^
1 warning generated.

here is my code:

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

int main()
{

    char readDATA[64];
    char buffer[8];
    char data[16];

    FILE *fl = fopen(data,"r");
    fgets(readDATA,64,fl);
    fread(buffer,1,512,data);
    printf("%s",readDATA);

    return 0;
}

I try to open a path or "random" file please help.

Answer 1

According to manual page of fread()

The function fread() reads nmemb elements of data, each size bytes long, from the stream pointed to by stream, storing them at the loca‐ tion given by ptr.

size_t fread(void *ptr, size_t size, size_t nmemb, FILE *stream);

Last argument of fread() is the FILE *stream that means file from where you want to read something and store into buffer .

Replace

 fread(buffer,1,512,data); /* last argument is wrong */

with

fread(buffer,1,512,f1);

Also check the return value of fopen()

FILE *f1 = fopen("data","r"); /* it will try to open a file called "data" in current working directory, you can take input from user also */
if(f1 == NULL) {
  fprintf(stderr, "file not present\n");
  return 0;
}

your intention may be like this

char data[16];/* it doesn't contain anything, so take the input from user or assign directly */
printf("enter the file name\n");
scanf("%s",data);
FILE *f1 = fopen(data,"r"); 
    if(f1 == NULL) {
      fprintf(stderr, "file not present\n");
      return 0;
    }