C Basics

Quick Reference

Essential format specifiers:

Variable declaration:

int count = 0;          // Always initialize
double gpa = 3.5;
char letter = 'A';      // Single quotes for chars

Common Pitfalls

• Uninitialized variables – Local variables contain garbage. Always assign before reading.
• Missing & in scanf – scanf("%d", x) is wrong. Use scanf("%d", &x).
• Wrong format specifier – %d for a double gives garbage. Use %f.
• Missing newline – Output may not appear until \n flushes the buffer.