ferror() in C
Last Updated :
03 Feb, 2025
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In C, ferror() is a built-in function used to check errors in files during file operations. It provides a simple way to do file operations without any interruption in your C program.
Syntax
ferror() is a standard library function defined in <stdio.h> file.
ferror(fptr)
Parameter:
- Take as a file stream in parameter.
Return Value:
- If the file has error, it returns a non-zero value.
- Otherwise, it returns 0.
Note: To check error in file using ferror(), file must be open before it.
Examples of ferror()
The following examples demonstrate the use of ferror() in C programs.
Check Error When Writing Data
#include <stdio.h>
int main() {
FILE *fptr = fopen("gfg.txt", "w");
// Write data to the file
fprintf(fptr, "Hello, GFG!");
// Check error after writing data into file
if(ferror(fptr)==0)
printf("Data written successfully.");
fclose(fptr);
return 0;
}
Output
Data written successfully.
Check Error When Read Data
#include <stdio.h>
int main() {
FILE *fptr = fopen("gfg.txt", "w+");
fprintf(fptr, "GeeksForGeeks!");
rewind(fptr);
char d[14];
while (fscanf(fptr, "%s", d) != EOF)
// check error after reading data from file
if(ferror(fptr)==0){
for(int i=0; i<sizeof(d); i++){
printf("%c", d[i]);
}
printf("\nNo error, Data read successfully");
}
fclose(fptr);
return 0;
}
Output
GeeksForGeeks! No error, Data read successfully
