优化以下C程序使其更简洁：#include stdioh#include ctypehchar get_choicevoid;char get_firstvoid;int mainvoid int choice; char ch; float num1 num2; while choice = get_choice != q printfEnter first number; while s

#include <stdio.h> #include <ctype.h>

char get_choice(void); float get_num(void); char get_first(void);

int main(void) { int choice; float num1, num2;

while ((choice = get_choice()) != 'q') {
    printf("Enter first number: ");
    num1 = get_num();

    printf("Enter second number: ");
    num2 = get_num();

    switch (choice) {
        case 'a':
            printf("%f\n", num1 + num2);
            break;

        case 's':
            printf("%f\n", num1 - num2);
            break;

        case 'm':
            printf("%f\n", num1 * num2);
            break;

        case 'd':
            while (num2 == 0) {
                printf("Enter a number other than 0: ");
                num2 = get_num();
            }

            printf("%f\n", num1 / num2);
            break;

        default:
            printf("Please respond with a, s, m,d, or q.\n");
            break;
    }
}

return 0;

}

char get_choice(void) { int ch; printf("Enter the operation of your choice:\n"); printf("a. add s. subtract\n"); printf("m. multiply d. divide\n"); printf("q. quit\n");

while ((ch = get_first()) != 'a' && ch != 's' && ch != 'm' && ch != 'd' && ch != 'q') {
    printf("Please respond with a, s, m,d, or q.\n");
}

return ch;

}

float get_num(void) { float num; char ch;

while (scanf("%f", &num) != 1) {
    while ((ch = getchar()) != '\n') {
        putchar(ch);
    }
    printf(" is not a number.\n");
    printf("Please enter a number,such as 2.5, -1.78E8, or 3: ");
}

return num;

}

char get_first(void) { int ch; ch = getchar();

while (isspace(ch)) {
    ch = getchar();
}

while (getchar() != '\n')
    continue;

return ch;