Using for loop:

#include<stdio.h>
int main( )
{
 int i;
 for(i=1; i<=10; i++)
 {
   printf("%d\t",i);
 }
 return 0;
}

Output:

1  2  3  4  5  6  7  8  9  10

Using while loop:

#include<stdio.h>
int main( )
{
 int i=1;
 while(i<=10)
 {
   printf("%d\t", i);
   i++;
 }
}

Output:

1  2  3  4  5  6  7  8  9  10

Using do…while loop:

#include<stdio.h>
int main( )
{
 int i=1;
 do{
   printf("%d\t", i);
   i++;
 }while(i<=10);
}

Output:

1  2  3  4  5  6  7  8  9  10

Syntax of for loop:

for(initialization; condition; increment/decrement)
{
  statement(s);
}

Syntax of while loop:

initialization;
while (condition)
{
 statement(s); 
 increment/decrement; 
}

Syntax of nested for loop:

for(initialization; condition; increment/decrement)
{
  for(initialization; condition; increment/decrement)
     {
        statement(s);
     }
}

Syntax of nested do…while loop:

do {
   statement(s);
} while(condition);

Program Code:

#include <stdio.h>
int main()
{
    char c;
    int LowercaseVowel, UppercaseVowel;

    printf("Enter an alphabet: ");
    scanf("%c", &c);

    LowercaseVowel = (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u');

    UppercaseVowel = (c == 'A' || c == 'E' || c == 'I' || c == 'O' || c == 'U');

    if (LowercaseVowel || UppercaseVowel)
        printf("%c is a vowel.", c);
    else
        printf("%c is a consonant.", c);
    return 0;
}

Output:

Enter an alphabet: Y
Y is a consonant.

Program Code:

#include <stdio.h>
int main()
{
    long long n;
    int count=0;
    printf("Enter an integer: ");
    scanf("%lld", &n);
    while(n!=0)
    {
        n = n/10;
        ++count;
    }
    printf("Number of digits: %d",count);
}

Output:

Enter an integer: 45729
Number of digits: 5

Program Code:

#include<stdio.h>
int main()
{
   int i, j;
   int count = 1;
   for (i = 1; i <= 5; i++)
    {
      for (j = 0; j < i; j++)
      {
         printf("%d\t", count);
         count++;
      }
        printf("\n");
    }
   return 0;
}

Output:

1
2       3
4       5       6
7       8       9       10
11      12      13      14     15

Program Code:

#include<stdio.h>
int main( )
{
 int i,j,rows;
 printf("Enter the number of rows:");
 scanf("%d",&rows);
 for(i=1;i<=rows;i++)
 {
   for(j=1;j<=i;j++)
   {
     printf("%d ",j);
   }
   printf("\n");
 }
}

Output:

Enter the number of rows:10
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6 7
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9 10

Program Code:

#include<stdio.h>
int main( )
{
 int i,j,rows;
 printf("Enter the number of rows:");
 scanf("%d",&rows);
 for(i=1;i<=rows;i++)
 {
   for(j=i;j>0;j--)
   {
     printf("* ");
   }
   printf("\n");
 }
}

Output:

Enter the number of rows:7
*
* *
* * *
* * * *
* * * * *
* * * * * *
* * * * * * *

Program Code:

#include<stdio.h>
int main( )
{
 int i,j;
 for(i=1;i<=5;i++)
 {
   for(j=i;j>0;j--)
   {
     printf("%d ",j);
   }
   printf("\n");
 }
}

Output:

1
2 1
3 2 1
4 3 2 1
5 4 3 2 1