4.13問題

1.

它是合法的，執行了加減乘除操作，但沒有賦值

2.

x =  expression

3.

合法

4.

if 後面用;空語句，或者else的條件該到用if的， 用!就可以.

5.

0

1

2

3

4

5

6

7

8

9

6.

個人感覺都差不多。水平有限

7.

少了{}，while的執行體就是第一個語句

正確的

while ((ch = getchar()) != EOF) {
        checksum += ch;
        putchar(ch);
    }
    
    printf("chechsum = %d\n", checksum);

8.

無論條件是否成立，都需要執行一次的環境下

9.

odd
even
odd
odd
even
odd

10.

int main(void)
{
    int i;
    
    scanf("%d", &i);
    
    for (; i > 0; i--) {
        printf("\n");
    }
    
    
    return EXIT_SUCCESS;
}

11.

int main(void)
{
    int x, y, a, b;
    
    scanf("%d %d %d %d", &x, &y,&a,&b);
    
    
 
if (x < y || a >= b) {
        printf("WRONG\n");
    }
    else
        printf("RIGHT\n");
    
    
    return EXIT_SUCCESS;
}

12.

int main(void)
{
    int in_year;
    int leap_year;
    
    scanf("%d", &in_year);
    if ((in_year % 4 == 0 && in_year % 100 != 0) || in_year % 400 == 0
 
) {
        leap_year = 1;
    }
    else
        leap_year = 0;
    
    printf("leap_year is %d\n", leap_year);
    
    
    return EXIT_SUCCESS;
}

13.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "t_c.h"




int main(void)
{
    int in_num;
    
    while (scanf("%d", &in_num) != 0) {
        switch (in_num) {
            case 1:
                printf("who\n");
                break;
            case 2:
                printf("waht\n");
                break;
            case 3:
                printf("when\n");
                break;
            case 4:
                printf("where\n");
                break;
            case 5:
                printf("why\n");
                break;
            default:
                printf("don't know");
                break;
        }
    }
    
    
    return EXIT_SUCCESS;
}

14.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "t_c.h"

static int full_num = 10;


void
eat_hamberger(void)
{
    printf("eat one hamberger\n");
    full_num--;
}

int
hungry(void)
{
    return full_num;
}


int main(void)
{
    while (hungry()) {
        eat_hamberger();
    }
    
    
    return EXIT_SUCCESS;
}

15.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "t_c.h"

static int full_num = 0;


void
eat_hamberger(void)
{
    printf("eat one hamberger\n");
    full_num--;
}

int
hungry(void)
{
    if (full_num > 0)
        return 1;
    else
        return 0;
}


int main(void)
{
    
    do {
        eat_hamberger();
    } while (hungry());
    
    return EXIT_SUCCESS;
}

16.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "t_c.h"

int main(void)
{
    
    int precipitsting;
    int temperature;
    
    scanf("%d%d", &precipitsting, &temperature);
    
    if (precipitsting == 1) {
        if (temperature < 32)
            printf("snowing\n");
        else
            printf("raining\n");
    }
    else
    {
        if (temperature < 60) {
            printf("cold\n");
        }
        else
            printf("warm\n");
    }

    
    return EXIT_SUCCESS;
}