13. C program to print ASCII values of all characters.
#include <stdio.h>

int main() {
printf ("***ASCII VALUES***\n");
for(int i =1; i<=256; i++){
printf ("%d --> %c\n",i,i);
}
return 0;
}

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;
}