我的阶乘和幂函数在不应该且不知道如何解决的情况下输出数百万的数字（在c中）

Question

I am trying to write a sort of calculator program and i can get everything but my factorial and power functions to work. They output a number in the millions no matter how small the number is and i don't see a problem with the code. (I just started learning C recently so assume the extent of my knowledge is everything in this code)

int iFactorial(num1){//needs help returns a number in the millions no matter what

    int i, factorial=1;
    printf("Enter a positive number: ");
    scanf("%d", &num1);
    for(i=1; i<=num1; i++)
            factorial*=i;
            printf("The factorial is %i", &factorial);
    return 0;

}
int fPower(num1,num2){//needs help, same as above
    int i, number = 1;
    printf("Enter the number you want to raise to a power: \n");
    scanf("%d", &num1);
    printf("Enter the exponent: ");
    scanf("%d", &num2);

    for(i=0; i<num2; i++)
        number*=num1;
        printf("%d to the %d equals %d", &num1, &num2, &number);
    return 0;  
}

Answer 1

You are using & in the print statement that prints the address of the variable used. Correct the statements in their respective function as follows :

printf("The factorial is %i", factorial);

printf("%d to the %d equals %d", num1, num2, number);

Answer 2

Your printf for the factorial and power cases are mal-formed, you are passing the arguments by pointer; you need to pass them by value.

After that, you'll realise quickly that you'll overflow the int type in the factorial and power cases. An int in general is only good up to and including 7! in truly portable C++. Consider using an unsigned long long , which will give you values up to and including 21! . Use "%ull" for an unsigned long long in the formatter.

Finally, pass the types explicitly to your functions in C: your style has been explicitly disallowed since C99.

Answer 3

You're using the wrong format specifiers to printf to print the results, and you're not passing the actual values you want to print:

printf("The factorial is %i", &factorial);

You're passing in the address of factorial instead of its value, so it's printing that instead. Just pass the result directly instead of its address:

printf("The factorial is %i", factorial);