Using return codes - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return success from main.

C

int main() {
    return [1];
}

Drag options to blanks, or click blank then click option'

AEXIT_SUCCESS

B1

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 1 or -1 means an error occurred.

Using EXIT_SUCCESS requires including .

Returning 0 from main means the program ended successfully.

2fill in blank

medium

Complete the code to return an error code 1 from main.

C

int main() {
    return [1];
}

Drag options to blanks, or click blank then click option'

A1

B0

CEXIT_FAILURE

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 0 means success, not error.

EXIT_FAILURE requires including .

Returning 1 from main indicates an error occurred.

3fill in blank

hard

Fix the error in the return statement to indicate failure.

C

int main() {
    return [1];
}

Drag options to blanks, or click blank then click option'

A2

B0

CEXIT_SUCCESS

DEXIT_FAILURE

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 0 means success, not failure.

Using numbers like 2 is less clear than EXIT_FAILURE.

Using EXIT_FAILURE clearly shows failure and is portable.

4fill in blank

hard

Fill both blanks to return success or failure based on condition.

C

int check(int value) {
    if (value > 0) {
        return [1];
    } else {
        return [2];
    }
}

Drag options to blanks, or click blank then click option'

AEXIT_SUCCESS

BEXIT_FAILURE

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 and 1 directly without macros.

Returning success for negative values.

Return EXIT_SUCCESS for positive values and EXIT_FAILURE otherwise.

5fill in blank

hard

Fill all three blanks to return codes based on input.

C

int status(int code) {
    switch(code) {
        case 0:
            return [1];
        case 1:
            return [2];
        default:
            return [3];
    }
}

Drag options to blanks, or click blank then click option'

AEXIT_SUCCESS

BEXIT_FAILURE

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Returning 0 for failure cases.

Not handling default case properly.

Return EXIT_SUCCESS for 0, EXIT_FAILURE for 1, and 1 for others.

Practice

1. What does a return code of 0 usually mean in C functions?

easy

A. The function completed successfully

B. The function encountered an error

C. The function did not run

D. The function returned a pointer

Solution

1. Step 1: Understand return codes meaning

   In C, a return code of 0 typically means success or no error.

2. Step 2: Interpret the code 0

   Since 0 means success, the function completed its task without problems.

3. Final Answer:

   The function completed successfully -> Option A

4. Quick Check:

   Return code 0 = success [OK]

Hint: Remember: 0 means success, non-zero means error [OK]

Common Mistakes:

• Thinking 0 means error
• Confusing return code with function output
• Assuming non-zero means success

2. Which of the following is the correct way to return an error code from a C function?

easy

A. return 0;

B. return 'error';

C. return -1;

D. return true;

Solution

1. Step 1: Identify valid return types for error codes

   Return codes are integers, so returning a number like -1 is valid for error.

2. Step 2: Check each option

   return 0; returns 0 (success), B returns a multi-char constant (invalid), C returns true (boolean, invalid in C), D returns -1 (valid error code).

3. Final Answer:

   return -1; -> Option C

4. Quick Check:

   Use integer codes for errors [OK]

Hint: Return integer codes; negative often means error [OK]

Common Mistakes:

• Returning strings instead of integers
• Using boolean values in C return codes
• Returning 0 for errors

3. What will be the output of this C program?

#include <stdio.h>
int check(int x) {
    if (x > 0) return 0;
    else return 1;
}
int main() {
    int result = check(-5);
    printf("Return code: %d\n", result);
    return 0;
}

medium

A. Return code: 1

B. Return code: -5

C. Return code: 0

D. No output

Solution

1. Step 1: Analyze the check function behavior

   If x > 0, it returns 0; otherwise, it returns 1.

2. Step 2: Apply input value -5

   Since -5 is not greater than 0, the function returns 1.

3. Final Answer:

   Return code: 1 -> Option A

4. Quick Check:

   Input -5 <= 0, so return 1 [OK]

Hint: Check conditions carefully to find returned code [OK]

Common Mistakes:

• Assuming negative input returns 0
• Confusing return value with input
• Ignoring else branch

4. Identify the error in this C function that uses return codes:

int process(int val) {
    if (val == 0)
        return 0;
    else
        return;
}

medium

A. Using 0 as success code

B. No error, code is correct

C. Function should return void

D. Missing return value in else branch

Solution

1. Step 1: Check function return type and return statements

   The function returns int, so every return must have an int value.

2. Step 2: Identify missing return value

   The else branch has 'return;' without a value, which is invalid for int return type.

3. Final Answer:

   Missing return value in else branch -> Option D

4. Quick Check:

   int functions must return int always [OK]

Hint: Every return in int function must return int value [OK]

Common Mistakes:

• Returning nothing in non-void function
• Confusing void and int return types
• Ignoring compiler warnings

5. You want to write a function int saveData() that returns 0 on success, 1 if file not found, and 2 if write error. Which is the best way to handle these return codes in main()?

hard

A. Ignore the return code and always print "Success"

B. Check if return code is 0, else print error message based on code

C. Return the code from main without checking

D. Use return codes only for debugging, not in main

Solution

1. Step 1: Understand return codes purpose

   Return codes help main know if saveData succeeded or failed and why.

2. Step 2: Choose proper handling in main

   Main should check if return code is 0 (success), else print specific error messages for 1 or 2.

3. Final Answer:

   Check if return code is 0, else print error message based on code -> Option B

4. Quick Check:

   Use return codes to handle errors clearly [OK]

Hint: Check return codes to handle errors clearly [OK]

Common Mistakes:

• Ignoring return codes in main
• Printing success without checking
• Using return codes only for debugging