Programming Errors in C Language

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programming_language)">Programming errors are also known as bugs or faults, and the process of fixing them is called debugging. Programming errors in C can lead to unexpected behavior in your software if not addressed promptly.

These errors can be detected either during compilation or execution. Therefore, it is essential to eliminate these errors for successful program execution.

There are primarily five types of errors in C programming:

1. Syntax Error:
   Syntax errors, also called compilation errors, occur during compilation. They are caused by typing mistakes or failure to adhere to the syntax rules of the programming language. These errors are often made by beginners and can be easily corrected.

For example:

Correct: int a; // This is the correct form
Incorrect: Int a; // This is an incorrect form

Common syntax errors include missing parentheses, attempting to use a variable without declaring it, and forgetting the semicolon at the end of a statement.

Let’s illustrate with an example:

#include <stdio.h>
int main()
{
    a = 10; // Error: 'a' is undeclared
    printf("The value of a is : %d", a);
    return 0;
}

2. Run-time Error:
   Run-time errors occur during program execution, even after successful compilation. These errors happen when the program cannot perform an operation correctly. A common example is division by zero. Run-time errors can be challenging to locate since the compiler does not identify them.

For example:

#include <stdio.h>
int main()
{
    int a = 2;
    int b = 2 / 0; // Error: Division by zero
    printf("The value of b is : %d", b);
    return 0;
}

3. Linker Error:
   Linker errors occur when the executable file of the program is not generated. This can happen due to incorrect function prototypes or using the wrong header files. For instance, if a file contains a function, ‘sub()’, and its declaration and definition are in a different file, such as ‘func.c,’ a linker error can occur if the definition of ‘sub()’ is missing at execution time. Common linker errors include using ‘Main()’ instead of ‘main()’.

For example:

#include <stdio.h>
int Main() // Error: Should be 'main()' not 'Main()'
{
    int a = 78;
    printf("The value of a is : %d", a);
    return 0;
}

4. Logical Error:
   Logical errors result in undesired program output. They produce incorrect results even though the code is free of syntax and compilation errors. Logical errors are often made by beginners and depend on the developer’s logical reasoning. A sound understanding of logic reduces the likelihood of such errors.

For example:

#include <stdio.h>
int main()
{
    int sum = 0; // Variable initialization
    int k = 1;
    for (int i = 1; i <= 10; i++); // Logical error: Semicolon misplaced
    {
        sum = sum + k;
        k++;
    }
    printf("The value of sum is %d", sum);
    return 0;
}

In the above code, the semicolon (;) after the for loop leads to incorrect program output.

5. Semantic Error:
   Semantic errors occur when statements are not understandable by the compiler. Cases of semantic errors include using an uninitialized variable, type compatibility issues, errors in expressions, and array index out-of-bounds.

For example:

#include <stdio.h>
int main()
{
    int a, b, c;
    a = 2;
    b = 3;
    c = 1;
    a + b = c; // Error: Invalid statement
    return 0;
}

In the above code, the statement ‘a + b = c’ is incorrect because two operands cannot be used on the left side.

These are the common types of programming errors in C.