STEP 2 Review: Arithmetic, Assignment, and Increment

🧮 Arithmetic operators

• Precedence: * / % before + and -
• Parentheses ( ) makes the order explicit

⚠️ Integer ÷ integer = integer (fraction discarded)

printf("%d", 7 / 2);       // 3 (fraction discarded) 
printf("%f", 7.0 / 2);     // 3.500000
printf("%f", (double)7 / 2); // 3.500000 (cast) 

• Make either operand floating-point to perform floating-point division
• cast (double)x explicitly converts the type

🔄 Compound assignment

• update the variable itself : a common pattern

⏫ Increment and decrement

int a = 5;
a++;   // a = 6 (add 1 to a) 
a--;   // a = 5 (subtract 1 from a) 

// Prefix versus postfix (different inside expressions) 
int x = 5, y;
y = x++; // y=5, x=6 (increase x after using its old value for y) 
y = ++x; // y=7, x=7 (increase x first, then use its new value for y) 

• As standalone statements a++;, prefix and postfix have the same effect
• Inside an expression , their values differ

🐞 Basic printf debugging

int a = 10, b = 3;
printf("a=%d b=%d\n", a, b);
int avg = (a + b) / 2;
printf("avg=%d\n", avg); // Expected:6.5 Actual:6 — integer division! 

• When a result differs from your expectation, print the values just before that operation
• Print both variable names and values to make the trace easier to follow