14. C program to find your age.
#include <stdio.h>
#define PRESENT_YEAR 2020
int main() {
printf ("***HOW OLD ARE YOU***\n");
int BORN_YEAR;
int AGE;
printf ("You have entered your born year\n");
scanf("%d",&BORN_YEAR);
if(BORN_YEAR > PRESENT_YEAR ){
printf("invalide number\nplease try again!");
}
AGE = PRESENT_YEAR - BORN_YEAR ;
printf ("This year you will be %d years old\n",AGE );
//To check your birth year was a leal year!
if((BORN_YEAR % 400 == 0) ||((BORN_YEAR % 400 == 0 ) && (BORN_YEAR % 100 !=0))){
printf ("you are borned in a leap year\n ");
}
else{
printf("you are not borned in a leal year\n");
}
return 0;
}

15. C program to find the factorial of a given number.
#include <stdio.h>

int factorial(int facto){
if((facto==1) || (facto==0)){
return 1;
}
else{
return facto * factorial(facto-1);
}
}

int main() {
printf("***FACTORIAL***\n\n");
int fact;
printf ("Enter a number for factorial\n");
scanf("%d",&fact);
printf("you have entered %d and its factirial is %d\n",fact,factorial(fact));
return 0;
}

16. C program to swap two numbers using function.
#include <stdio.h>
void swap(int a, int b){
a = a+b;
b = a-b;
a = a-b;
}
int main() {
int a,b;
scanf("%d %d",&a,&b);
printf("a = %d\nb= %d\n",a,b);
swap(a,b);
printf("a=%d\nb=%d",a,b);
return 0;
}

17. C program to find factors of a given number.
#include <stdio.h>

int main(){
int num, count =0;
printf("Enter a number: ");
scanf("%d", &num);
printf("factorial of %d are:\n", num);
for(int i =1; i<= num; i++){
if(num % i == 0){
printf("\t%d\n", i);
count++;
}
return 0;
}

18. C program to find n power of a number.
#include <stdio.h>

int main()
{

int a, b, temp, res=1;
printf("Enter a numbers: ");
scanf("%d", &a);
printf("Enter power of %d: ",a);
scanf("%d",&b);
for(int i =1; i<=b; i++){
temp = a;
res = res * temp;
}
printf("result = %d", res);

return 0;
}

16(a). Another way to swap two numbers.
#include <stdio.h>

int main() {
int a,b;
printf("Enter two number for swapping: ");
scanf("%d %d",&a,&b);
printf("a = %d\nb= %d\n",a,b);
a = a*b;
b = a/b;
a = a/b;
printf("a=%d\nb=%d",a,b);
return 0;
}

19. C program to print ABCD and abcd.
#include <stdio.h>

int main() {
char i,j;
printf("small letters\n");
for(i='a';i<='z';i++){
printf ("%c ",i);
}
printf("\n\nCAPITAL LATTERS\n");
for(j='A';j<='Z';j++){
printf ("%c ",j);
}

return 0;
}

20. C program to find multiplication of two matrices.
#include <stdio.h>

int main()
{
printf ("***matrices multiplication***\n");
int a[2][2], b[2][2], c[2][2];
int i, j;
printf("enterthe elements of 1st matric:\n");
for(i = 0;i< 2;i++){
for(j = 0;j< 2;j++)
scanf("%d",&a[i][j]);
}

printf("enter the elements of 2nd matric:\n");
for(i = 0;i< 2;i++){
for(j = 0;j< 2;j++)
scanf("%d",&b[i][j]);
}

printf ("resulted matric..\n");
for(i = 0;i< 2;i++){
for(j = 0;j< 2;j++){
c[i][j]=0;
for(int k=0; k<2; k++){
c[i][j] += a[i][k] * b[k][j];
}
printf ("%d ",c[i][j]);
}
printf ("\n");
}
return 0;

}
i

21. C program to swap two characters.
#include <stdio.h>

void character_swaping(char *a, char *b);

int main()
{
char ch1 = 's';
char ch2 = 'r';
printf("character before swaping:\nch1 = %c ch2 = %c\n",ch1, ch2);
character_swaping(&ch1, &ch2);
printf("character after swaping:\nch1 = %c ch2 = %c\n",ch1, ch2);
return 0;
}
void character_swaping(char *a, char *b){
char temp;
temp = *a;
*a = *b;
*b = temp;
}

22. C program to print numbers from 1 to 10 without using loop.
#include <stdio.h>

int res(int num){
static int s = 1;
if (s == num+1)
return 1;
printf ("%d ", s);
s++;
res(num);
}
int main() {
int p = 10;
res(p);
return 0;
}

23. C program to convert numbers into roman digit's.
#include<stdio.h>

int rom(int, char);
int roman(int n){
int m = n/1000;
n = n % 1000;
rom(m,'m');

int d = n /500;
n = n % 500;
rom(d,'D');

int c = n /100;
n = n % 100;
rom(c,'c');

int l = n /50;
n = n % 50;
rom(l,'L');


int x = n /10;
n = n % 10;
rom(x,'x');

int v = n /5;
n = n % 5;
rom(v,'v');

int i = n /1;
n = n % 1;
rom(i,'i');
return 0;
}

int rom(int q,char h){
for(int i =0;i<q;i++){
printf ("%c",h);
}
return 0;

}

int main() {

int num;
scanf("%d",&num);
printf("Roman value of %d is: ", num);
roman(num);
return 0;
}

If you've any query or doubt about these programs , kindly DM me , I'll try to solve them.
Thank you..
Happy Coding :)

24. C program to print all leap years in between 1 and 5000 using control statements.
#include <stdio.h>

int main()
{
for(int year = 1; year <= 5000; year++){
if(year % 4==0){
printf("year %d is a leap year\n", year);
}
}
return 0;
}

25. C program to add two matrices.
#include <stdio.h>

int main()
{
printf ("***matrices addition***\n");
int a[2][2], b[2][2], c[2][2];
int i, j;
printf("enter the elements of 1st matric:\n");
for(i = 0;i< 2;i++){
for(j = 0;j< 2;j++)
scanf("%d",&a[i][j]);
}

printf("enter the elements of 2nd matric:\n");
for(i = 0;i< 2;i++){
for(j = 0;j< 2;j++)
scanf("%d",&b[i][j]);
}

printf ("resulted matric..\n");
for(i = 0;i< 2;i++){
for(j = 0;j< 2;j++){
c[i][j] = a[i][j] + b[i][j];

printf ("%d",c[i][j]);
}
printf ("\n");
}
return 0;
}

26. C program to find individual digits without using if-else and switch case instructions.
#include <stdio.h>

char ind[][10] = {"zero","one","two","three","four","five", "six", "seven", "eight","nine"};
void find(int num){
int dg[10], count=0;
do{
dg[count] = num % 10;
num /= 10;
count++;
} while (num != 0);
for(int i = count -1; i >= 0; i--){
printf("%s ", ind[dg[i]]);
}
}

int main(){
int num;
printf ("enter a number: ");
scanf ("%d",&num);
find(num);
return 0;
}

27. C program to find sum of individual number.
#include<stdio.h>
int main(){
int num, sum;
scanf("%d",&num);
while(num>0){
sum += num % 10;
num /= 10;
}
printf("sum of individual digits is %d", sum);
return 0;
}\

28. C program to find whether a character is a vowel or not.
#include <stdio.h>

int main(){
char ch;
printf("Enter a character: ");
scanf("%c",&ch);
if(ch==97 ch==101 ch==105 ch==111 ch==117)
{
printf("%c is vowel!",ch);
}
else
{
printf("%c is a constant!",ch);
}
return 0;
}

#Explanation:
The correct answer is 3rd becoz , as you all know that '//' are used for give a comment, comment means compiler will skip these part of the code, and will execute next statement of the code, but if I write a comment , which will terminate with '\' symbol then compiler will skip the next line of the code and will execute the third line of the code and that's known as "Line splicing".
Hope you understood!
Happy coding :)