Text reading end judgment

1. Whether the reading of text file is finished , Determine whether the return value is EOF （ fgetc ）, perhaps NULL （ fgets ）

for example ： fgetc Judge whether it is EOF .

fgets Determine whether the return value is NULL .

2. Judgment of reading end of binary file , Judge whether the return value is less than the actual number to be read . for example ： fread Judge whether the return value is less than the actual number to be read

#include <stdio.h>
#include <stdlib.h>
int main(void)
{
    int c; //  Be careful ：int, Not char, Ask to deal with EOF
    FILE* fp = fopen("test.txt", "r");
    if(!fp) {
        perror("File opening failed");
        return EXIT_FAILURE;
   }
 //fgetc  When reading fails or the end of the file is encountered , Will return to EOF
    while ((c = fgetc(fp)) != EOF) //  standard C I/O Read file cycle 
   { 
       putchar(c);
   }
// Judge why it ended 
    if (ferror(fp))
        puts("I/O error when reading");
    else if (feof(fp))
        puts("End of file reached successfully");
    fclose(fp);
}


 Examples of binary files ：
#include <stdio.h>
enum { SIZE = 5 };
int main(void)
{
    double a[SIZE] = {1.,2.,3.,4.,5.};
    FILE *fp = fopen("test.bin", "wb"); //  Binary mode must be used 
    fwrite(a, sizeof *a, SIZE, fp); //  Write  double  Array of 
    fclose(fp);
    double b[SIZE];
    fp = fopen("test.bin","rb");
    size_t ret_code = fread(b, sizeof *b, SIZE, fp); //  read  double  Array of 
    if(ret_code == SIZE) {
        puts("Array read successfully, contents: ");
        for(int n = 0; n < SIZE; ++n) printf("%f ", b[n]);
        putchar('\n');
   } else { // error handling
       if (feof(fp))
          printf("Error reading test.bin: unexpected end of file\n");
       else if (ferror(fp)) {
           perror("Error reading test.bin");
       }
   }
    fclose(fp);
}