The document discusses loops in C programming. It explains that loops are used to repeatedly execute a set of statements. There are three types of loops: while loops, for loops, and do-while loops. It provides examples of using while and for loops to print sequences of numbers and characters. It also includes practice problems for readers to write loops that perform tasks like taking user input, calculating sums and averages, and counting digits in a number.

1. Programming with C
LOOPS
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2. Repetition
Loops: We want to use loops when we want to keep repeating a set of
statements.
There are various ways to use loops:
1. While Loop
2. For Loop
3. Do-While Loop (We will skip this one for now)
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3. While
Syntax:
while (condition){
statements
}
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4. While
Write a program to print numbers 1 to 10 using while loop
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#include<stdio.h>
int main(){
int i = 1;
while (i<=10){
printf ("%d ", i);
i++;
}
}

5. While
Write a program that prints the following series:
2,4,8,16,32,64,128
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int number = 2;
while (number <=128){
printf ("%d ", number);
number*=2;
}

6. While
Write a program to print the following series using loop
2,-4,6,-8,10,-12
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7. While
Write a program to print the following series using loop
2,-4,6,-8,10,-12
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int c = 1;
int x;
while (c<=6){
if (c%2 == 0){
x = c* (-2);
}
else {
x = c*2;
}
printf("%d ", x);
c++;
}

8. For Loop
Syntax:
for (start statement; repeat condition; loop update){
Statements
}
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9. For Loop
Print odd numbers from 1 to 20 using for loop.
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int i;
for (i = 1; i<=20; i+=2){
printf("%d ", i);
}

10. Practice
Write a program to print all the letters from a to z.
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char ch;
for (ch= 'a'; ch<='z'; ch+=1){
printf("%cn" , ch);
}

11. Practice
Write a C program that takes 10 numbers as input and prints “Even” if a
number is even and “Odd” if a number is odd.
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#include<stdio.h>
int main(){
int x,i;
printf("Enter 10 numbersn");
for (i=1;i<=10;i++){
scanf("%d", &x);
if (x%2==0){
printf("Evenn");
}
else {
printf("Oddn");
}
}
}

12. Practice
Take 10 numbers as input and print their sum and average.
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#include<stdio.h>
int main(){
int x,i;
float average;
int sum = 0;
printf("Enter 10 numbersn");
for (i=1;i<=10;i++){
scanf("%d", &x);
sum+=x;
}
printf("The sum is = %dn", sum);
average = sum/10;
printf("The average is = %f", average);
}

13. Practice
Write a C program to print the following series using loop:
1,3,9,27,81
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#include<stdio.h>
#include<math.h>
int main(){
int x,i;
for (i=0; i<=4; i++){
x = pow(3,i); //3 to the power i
printf("%d ", x);
}
}

14. Practice
Write a program that takes a number input and prints the number of
digits in that number.
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#include<stdio.h>
int main(){
int x;
scanf("%d", &x);
int count = 0;
while (x!=0){
count ++;
x = x/10;
}
printf ("Total number of digits = %d", count);
}

15. For more practice problems:
http://www.codeforwin.in/2015/06/for-do-while-loop-programming-
exercises.html
http://www.w3resource.com/c-programming-exercises/for-
loop/index.php
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16. THE END
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