// Initialize rand()'s sequence. A typical seed value is the return value of time()
srand(someSeedValue);

//...

long range = 150000; // 100000 + range is the maximum value you allow
long number = 100000 + (rand() * range) / RAND_MAX;

您可能需要使用大于 code>和数字如果（100000 + range）将超过其最大值。

You may need to use something larger than a long int for range and number if (100000 + range) will exceed its max value.