1. CSCE 206 Lab Structured Programming in C
Fall 2018
Lecture 3
Luna BACKES

2. Today’s objective If-else logic block If - else if - else logic block
switch logic block

3. if-else if (condition_expression) {
// code to be executed if the // condition_expression is true
statements; }
else
// code to be executed if the
// condition_expression is false

4. Sample Code-1 #include <stdio.h> int main(void) { int a;
printf("Enter a number:"); // Asks user for input
scanf("%d", &a);
if (a > 0)
printf("%d is a positive number", a); }
else
printf("%d is not a positive number", a);
return 0;

5. if-else if-else if (condition1) {
// code to be executed if condition1 is true
} else if (condition2)
// code to be executed if condition2 is true }
else if (condition3)
// code to be executed if condition3 is true …
else
// code to be executed if all conditions are false

6. Sample Code-2
#include <stdio.h> int main(void) { int a; printf("Enter a number:"); // Asks user for input scanf("%d", &a); if (a>0) printf("%d is a positive number", a); } else if (a<0) printf("%d is a negative number", a); else printf("%d is zero",a); return 0;

7. Operators

8. Sample Code-3
#include <stdio.h> int main(void) { int a; printf("Enter a number:"); // Asks user for input scanf("%d", &a); if (a > 0 || a == 0) printf("%d is not a negative number", a); } else printf("%d is a negative number", a); return 0;

9. Nested if-else block if ( Boolean_expression1) {
/* Executes when the Boolean expression 1 is true */
if ( boolean_expression2)
/* Executes when the Boolean expression 2 is true */ }

10. Sample Code-4
#include <stdio.h> int main(void) { int a; printf("Enter a number:"); // Asks user for input scanf("%d", &a); if (a >= 0) if(a == 0) printf("%d is zero", a); } else printf("%d is a positive number", a); printf("%d is a negative number", a); return 0;

11. switch case

12. Sample Code-5
#include <stdio.h> int main(void) { int a; printf("Enter a number:"); // Asks user for input scanf("%d",&a); switch(a) case 0: printf("Zero"); break; } case 1: printf("One"); default: printf("No data"); return 0;

13. Now it’s your turn!

14. Practice Problem-1
Write a program that takes an integer as input and determines whether it is odd or even. It gives a proper sentence as output.
Tips: Use if-else block

15. Practice Problem-2
Write a program that takes 3 integers as input and prints out the largest number of them.
Tips: Use if-else if-else block

16. Practice Problem-3
Try Problem-1 using switch case.

17. Practice Problem-4
Write a C program that gets a character from the input and outputs whether the character was a vowel or a consonant.

18. Practice Problem-5
Write a C program that gets 3 floats from the input that represent the sides of a triangle, and outputs whether the triangle is equilateral, isosceles or scalene.

19. Practice Problem-6
Write a C program that gets a number (single digit) from the input and outputs the number in words.
For example:
Input: 3
Output: Three