c语言中将输入的正整数进行逆向输出。

c语言中将输入的正整数进行逆向输出。

1、do语句结合while语句

#include <stdio.h>

int main(void)
{
    int i;
    puts("please input an integer.");
    do
    {
        printf("i = "); scanf("%d", &i);
        if (i <= 0)
            puts("the range is > 0");
    }
    while (i <= 0);
    
    if (i > 0)
        printf("the reversed: ");
    while (i > 0)
    {
        printf("%d", i % 10);
        i /= 10;
    }
    return 0;
}

 ↓

#include <stdio.h>

int main(void)
{
    int i;
    puts("please input an integer.");
    do
    {
        printf("i = "); scanf("%d", &i);
        if (i <= 0)
            puts("the range is > 0");
    }
    while (i <= 0);
    
    int reversed = 0;
    while (i > 0)
    {
        reversed = reversed * 10 + i % 10;
        i /= 10;
    }
    printf("the reversed: %d\n", reversed);
    return 0;
}

2、编写函数， 没有形参的函数

#include <stdio.h>

int func1(void)
{
    int i;
    puts("please input an integer.");
    do
    {
        printf("i = "); scanf("%d", &i);
        if (i <= 0)
            puts("the range is > 0.");
    }
    while (i <= 0);
    return i;
} 

int func2(int x)
{
    int i = 0;
    while (x > 0)
    {
        i = i * 10 + x % 10;
        x /= 10;
    }
    return i;
}

int main(void)
{
    int x = func1();
    printf("the reversed: %d\n", func2(x));
    return 0;
}