1
LAB 2: C BASICS
ITS100: Computer and Programming Lab.
Section 1
Instructor: Wirat Chinnan
TAs:
Ms. Sasirassamee Buavirat
Mr. Thanasan Tanhermhong (Tum)
Ms. Pattheera Panitsuk (Fon+)
Mr. Pongsate Tangseng
Mr. Chinorot Wangtragulsang
Mr. Kanin Assantachai (Ob)
2
variable type
printf() and scanf()
%c
%d
%d
%ld
%f
%lf
3
printf()
• printf() is for output
4
scanf()
• scanf() is for input.
• Do not forget & in front of variable names.
5
Float and Integer
float d;
int i;
d
i
2.54
5.8
1.3
3.00
2
5
1
3
6
Print Integer with getting input from keyboard
#include <stdio.h>
int main()
{
int n1;
printf(“Enter a Number: “);
scanf(“%d”,&n1);
printf(“n1 = %d\n”, n1);
return 0;
}
Enter a Number: 10
n1 = 10
7
Print Integer with getting input from keyboard
#include <stdio.h>
int main()
{
int n1,n2;
printf(“Enter 1#: “);
scanf(“%d”,&n1);
printf(“Enter 2#: “);
scanf(“%d”,&n2);
printf(“output = %d %d\n”, n1,n2);
return 0;
Enter 1#: 10
}
Enter 2#: 20
output = 10 20
8
Reads in two integer and prints out the result of the
first number divided by the second number.
#include <stdio.h>
int main()
{
int n1,n2, ans;
printf(“Enter two numbers: ”);
scanf(“%d %d”,&n1,&n2);
ans = n1/n2;
// mathematic expression
printf(“Remainder = %d\n”, ans);
return 0;
Enter two Numbers: 21 6
}
Remainder = 3
9
Reads in two decimal and prints out the result of the
first number divided by the second number.
#include <stdio.h>
int main()
{
float n1,n2, ans;
printf(“Enter two numbers: ”);
scanf(“%f %f”,&n1,&n2);
ans = n1/n2;
printf(“Remainder = %f\n”, ans);
return 0;
Enter two Numbers: 21 6
}
Remainder = 3.500000
10
Reads in two integer and prints out the remainder of
the first number divided by the second number.
#include <stdio.h>
int main()
{
int n1,n2, ans;
printf(“Enter two numbers: ”);
scanf(“%d %d”,&n1,&n2);
ans = n1%n2; // % means modulo operation
printf(“Remainder = %d\n”, ans);
return 0;
Enter two Numbers: 22 6
}
Remainder = 4
11
Mathematical Functions
• #include<math.h>
• All of these functions require arguments in float and
return float
12
Finds the square root of an input.
#include <stdio.h>
#include <math.h>
int main()
{
float n1, ans;
printf(“Enter a number: ”);
scanf(“%f”,&n1);
ans = sqrt(n1);
printf(“square root = %f\n”, ans);
return 0;
}
Enter a number : 3
square root = 1.732051
13
Finds the power of an input.
#include <stdio.h>
#include <math.h>
int main()
{
int n1,n2, ans;
printf(“Enter two numbers: ”);
scanf(“%d %d”,&n1,&n2);
ans = pow(n1,n2);
printf(“n1 power n2 = %d\n”, ans);
return 0;
}
Enter two Numbers: 2 3
n1 power n2 = 8
14
To Do in Class
• Exercise 1 - 5
• Call your TA when you finished.
• You may take a break
• Be ready for the speed test at 15.00
15
Speed Test
• Speed test should be treated just like a real exam.
• Rules:
• No talking. Be quiet.
• No mobile phone.
• No electronic devices other than your PC
• No Internet
• No cheating
• Cheating will result in a severe penalty
• TAs will not help you (except when your PC crashes).
• Time allowed: 45 minutes.
16
Speed Test Instruction
• Write your name on the question sheet.
• Create all workspace on your ‘Desktop’ and set workspace’s
name follow: Sx_ID_Gx
Example : S1_5322793303_G1
(for Section 1 ID 5322793303 Group 1)
Example : S1_5322793303_G2
(for Section 1 ID 5322793303 Group 2)
• When you finished
• Raise your hand to signal the assigned TA
• TA grades your work
• Quietly leave the room
• DO NOT bring the question sheet out. Leave it on your table.