🔴 Advanced · Lesson 45

Error Handling in C

Error Handling

C does not have exceptions like some modern languages. We handle errors using return values, NULL, errno, perror() and careful checking.

Return Codes

C Language

#include <stdio.h>

int divide(int a, int b, int *result) {
    if(b == 0) return 0;   // failure
    *result = a / b;
    return 1;              // success
}

int main() {
    int ans;
    if(divide(10, 0, &ans))
        printf("Result = %d", ans);
    else
        printf("Error: divide by zero");
    return 0;
}

errno and perror

C Language

#include <stdio.h>
#include <errno.h>
#include <string.h>

int main() {
    FILE *fp = fopen("missing.txt", "r");
    if(fp == NULL) {
        perror("File error");
        printf("errno = %d\n", errno);
        printf("Message = %s", strerror(errno));
        return 1;
    }
    fclose(fp);
    return 0;
}

File Error Handling

C Language

FILE *fp = fopen("data.txt", "r");
if(fp == NULL) {
    printf("Unable to open file");
    return 1;
}

Memory Error Handling

C Language

int *arr = malloc(n * sizeof(int));
if(arr == NULL) {
    printf("Memory allocation failed");
    return 1;
}

Summary

Check return values of functions
Check NULL for file and memory operations
Use perror() for system error messages
Use clear return codes for your own functions
Handle errors early to avoid crashes

Error Handling

C में exceptions नहीं होते। Errors को return values, NULL, errno और perror() से handle किया जाता है।

Return Codes

C Language

if(b == 0) return 0;  // error
return 1;             // success

errno और perror

C Language

FILE *fp = fopen("missing.txt", "r");
if(fp == NULL) {
    perror("File error");
    return 1;
}

File Error

C Language

if(fp == NULL) {
    printf("Unable to open file");
    return 1;
}

Memory Error

C Language

int *arr = malloc(n * sizeof(int));
if(arr == NULL) {
    printf("Memory allocation failed");
    return 1;
}

सारांश

Function return values check करें
File और memory के लिए NULL check करें
perror system error message देता है
अपने functions में clear return codes रखें
Error को समय पर handle करें

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