Shadowing Variable

Description

A variable is declared with the same name as a variable in an outer scope, hiding the outer variable.

Common Causes

• Reusing variable names in nested scopes
• Using the same name for function parameters and global variables
• Declaring variables in for loops with names already used

Example of Error

Error Code

int x = 10;  // Global x

int main() {
    printf("Global x: %d\n", x);
    
    {
        int x = 20;  // Local x shadows global x
        printf("Local x: %d\n", x);
    }
    
    return 0;
}

Solution

Use different names for variables in different scopes to avoid confusion.

Corrected Code

int global_x = 10;  // Clearly named global variable

int main() {
    printf("Global x: %d\n", global_x);
    
    {
        int local_x = 20;  // Clearly named local variable
        printf("Local x: %d\n", local_x);
    }
    
    return 0;
}

Additional Tips

• Use descriptive variable names to avoid accidental shadowing
• Consider using prefixes for global variables
• Be aware of variable scope and lifetime
• Use compiler flags like -Wshadow to catch shadowing