else if, && and ||

Checked top to bottom

In a chain of if … else if … else, C checks each condition in order and runs only the first block whose condition is true.

&& means both must be true, || means at least one, ! flips true and false. marks >= 40 && marks < 60 is true for 40 to 59.

First match wins

#include <stdio.h>

int main() {
    int t = 35;
    if (t > 20) {
        printf("warm\n");
    } else if (t > 30) {
        printf("hot\n");
    } else {
        printf("cool\n");
    }
    return 0;
}

What does this print?

• warm
• hot
• warm hot

Exercise: Marks to grade

Read marks (0 to 100) and print the grade: 75 and above A, 60 to 74 B, 40 to 59 C, below 40 F.

Exercise: Leap year

Read a year and print Leap or Not leap.

A year is a leap year if it divides by 4, except years that divide by 100, unless they also divide by 400.

Break it: Break the biggest-of-three

This should print the biggest of three numbers. Find an input where it prints the wrong one.

#include <stdio.h>

int main() {
    int a, b, c, max;
    scanf("%d %d %d", &a, &b, &c);
    if (a > b) max = a;
    if (b > c) max = b;
    else max = c;
    printf("%d\n", max);
    return 0;
}

Input rules: three whole numbers between -1000 and 1000, separated by spaces.