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C++ How To Generate Random Numbers


Random Number

You can use the rand() function, found in the <cstdlib> library, to generate a random number:

Example

cout << rand();
Try it Yourself »

To get more control over the random number, for example, if you only want a random number between 0 and 100, you can use the following formula:

Example

// Generate a random number between 0 and 100
int randomNum = rand() % 101;

cout << randomNum;
return 0;
Try it Yourself »

Note: The examples above just outputs a random number once. They don't output different random numbers each time the program runs. To fix this, you can use the srand() function and add the time() function from the <ctime> library.

This will generate a random number from 0 to 100 each time the program runs:

Example

// Get a different random number each time the program runs
srand(time(0));

// Generate a random number between 0 and 100
int randomNum = rand() % 101;

cout << randomNum;
return 0;
Try it Yourself »


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