In this post, we will learn **how to print prime numbers from 1 to 100 using the C** Programming language.

In the previous post, you have seen** how to check whether a number is prime or not**. Today, we will print all the prime numbers lying between** 1 to 100** using the following approaches:

- Using For Loop
- Using While Loop

So, without further ado, let’s begin this tutorial.

**C Program to Print Prime Numbers From 1 to 100**

// C Program to Print Prime Numbers From 1 to 100 #include <stdio.h> int main(){ int i, num, count; // Checking for prime numbers for (num = 1; num <= 100; num++){ count = 0; for (i = 2; i <= num/2; i++){ if (num % i == 0){ count++; break; } } // Checking and Printing Prime Numbers if (count == 0 && num != 1){ printf("%d \n", num); } } return 0; }

**Output**

```
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61
67
71
73
79
83
89
97
```

**How Does This Program Work ?**

int i, num, count;

In this program, we have declared** three integer data type** variables named **i**, **num**, and **count**.

for (num = 1; num <= 100; num++){ count = 0; for (i = 2; i <= num/2; i++){ if (num % i == 0){ count++; break; } }

For every number, we check its factor. If that iteration of the for loop contains a factor, then count values increases.

// Checking and Printing Prime Numbers if (count == 0 && num != 1){ printf("%d \n", num); }

Now, all the numbers which don’t have a factor are prime numbers. We print all those numbers using** printf() **function.

**C Program to Print Prime Numbers From 1 to 100 Using While Loop**

// C Program to Print Prime Numbers From 1 to 100 Using While Loop #include <stdio.h> int main(){ int i, num = 1, count; // Checking for the factors while (num <= 100){ count = 0; i = 2; while (i <= num/2){ if (num % i == 0){ count++; break; } i++; } // Printing prime numbers if (count == 0 && num != 1){ printf("%d \n", num); } num++; } return 0; }

**Output **

```
2
3
5
7
11
13
17
19
23
29
31
37
41
43
47
53
59
61
67
71
73
79
83
89
97
```

**Conclusion**

I hope after going through this post, you understand **how to print prime numbers from 1 to 100 using the C** Programming language.

If you have any doubt regarding the program, then contact us in the comment section. We will be delighted to assist you.

**Also Read:**

Ismail// C Program to Print Prime Numbers From 1 to 100

#include

int main(){

int i, num, count;

// Checking for prime numbers

for (num = 1; num <= 100; num++){

count = 0;

for (i = 2; i <= num/2; i++){

if (num % i == 0){

count++;

break;

}

}

// Checking and Printing Prime Numbers

if (count == 0 && num != 1){

printf("%d \n", num);

}

}

return 0;

}

***I don't understand, if I put 0 at the start of count variable (ie, int i,num,count=0 like this) the code is not working. But if you put "count=0" inside the for loop it is working. Why is this happening?