How to generate a random number in a given range in C.

Examples:

Input : Lower = 50,
        Upper = 100,
        Count of random Number = 5 
Output : 91 34 21 88 29 
Explanation: lower is the lower limit of the 
range and upper is the upper limit of the range.
Output contains 5 random numbers in given range.

　　

As C does not have an inbuilt function for generating a number in the range, but it does have rand function which generate a random number from 0 to RAND_MAX. With the help of rand () a number in range can be generated as num = (rand() % (upper – lower + 1)) + lower

 

 

// C program for generating a 
// random number in a given range. 
#include <stdio.h> 
#include <stdlib.h> 
#include <time.h> 

// Generates and prints 'count' random 
// numbers in range [lower, upper]. 
void printRandoms(int lower, int upper, 
                            int count) 
{ 
    int i; 
    for (i = 0; i < count; i++) { 
        int num = (rand() % 
        (upper - lower + 1)) + lower; 
        printf("%d ", num); 
    } 
} 

// Driver code 
int main() 
{ 
    int lower = 5, upper = 7, count = 1; 

    // Use current time as 
    // seed for random generator 
    srand(time(0)); 

    printRandoms(lower, upper, count); 

    return 0; 
}