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 :)

29. C program to find whether a character is a upper case character or lower case character or special symbol or a number(by using switch case instructions).
#include <stdio.h>

int main(){
char ch;
int val =0;
printf("enter a character: ");
scanf("%c",&ch);
if(ch>= 97 && ch<= 122)
val = 1;
else if(ch>=65 && ch<90)
val = 2;
else if(ch>=33 && ch<= 64 || ch>=91 && ch<=96)
val = 3;
else if(ch >= 48 && ch<=57)
val = 4;
else
val = 0;
switch(val){
case 1:
printf("%c is a lower case alphabet",ch);
break;
case 2:
printf("%c is a upper case alphabet",ch);
break;
case 3:
printf("%c is a special symbol",ch);
break;
case 4:
printf("%c is a numerical digit",ch);
default:
printf("Another character");
}
return 0;
}

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30. C program to find factorial of a given number using Recursion.
#include <stdio.h>

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

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

31. C program to convert 24 hours clock into AM/PM.
#include <stdio.h>

int main() {
int i;
scanf("%d",&i);
if(i>=13 && i <= 24){
printf ("PM");
}
else{
printf ("AM");
}
return 0;
}

answer would be 'false' causes:
#explanation |Quiz. #4|

as we all know that when we use signed variable of any data type, first compiler will convert
it into unsigned value, proccess to convert signed into unsigned is that:
signed char = -23
1)binary of 23 is (00010111)
2)1's complement of (00010111) this : (11101000)
3)for convert it into unsigned add 1 into (11101000): 11101001 this is the binary of 233
and unsigned value of -23 is 233,
Now!
unsigned int i=23;
signed char c=-23;
if(i>c)
printf("true");
else
printf("false");

::: here we are comparing (23>233) which is false, so final answer would be false.

32. C program to find sum of all even integers between 0 to n.
#include <stdio.h>

int main() {
int n, num2, sum1 = 0;
scanf("%d",&n);
for(int i = 0; i < n; i++){
scanf("%d",&num2);
if(num2 % 2 ==0){
sum1= sum1+num2;
}
else{
continue ;
}
}
printf("%d",sum1);
return 0;
}

33. C program to convert numbers from decimal to binary.
#include <stdio.h>

int main() {
printf("***DECIMAL TO BINARY***\n");
int num ,i=0;
int arr[10];
scanf("%d",&num);
printf ("you have entered %d\nand its binary is: ",num);
while(num>0){
arr[i] = num % 2;
num = num / 2;
i++;

}
for(int j= i-1;j>=0; j--){
printf ("%d ",arr[j]);
}
return 0;
}

34. C program to convert numbers from octal to decimal.
#include <stdio.h>
#include <math.h>

int main()
{
long int Dec=0, Oct;
int up=0;
printf("enter a number: ");
scanf("%ld",&Oct);
while(Oct != 0){
Dec += (Oct %10) * pow(8,up++);
Oct /= 10;
}
printf("res=%ld",Dec);
return 0;
}

35. C program to convert lower case character into upper case character (without using string functions).
#include <stdio.h>

int main()
{
char lower;
int upper;
printf("enter a lower case character: ");
scanf("%c",&lower);
if(lower >=97 && lower<= 122){
upper = lower - 32;
printf("%c",upper);
}
return 0;
}