c - 难以理解循环

Question

我是 C 编程的新手，我很难掌握如何在 C 编程中使用 while 和 if 函数。

目前我正在粗略地尝试启动我的程序。我目前在我的“if 语句”处收到错误消息“预期表达式”，但我认为代码有更多错误，因为它不会执行我正在查找的内容。

理想情况下，我想这样做，以便用户将继续收到相同的错误消息，直到他们正确输入 1-3 之间的数字，然后一旦他们输入正确的数字，它就会存储它并继续接下来的步骤。抱歉，我对此很陌生，我一直对我正在阅读的有关循环和 if 语句的所有不同教程感到困惑。

如有任何帮助，我们将不胜感激。

#include <stdio.h>

int main(void)
{
    printf("Welcome to the ROBOT GAME!\n"
           "To help you visualize draw a three by three board on a piece of paper.\n"
           "Please enter the column of your starting point.\n"
            "Keep numbers in the range of one to three.\n");
    int a;
    scanf("%i", &a);
    while(a<1||a>3)
    {
        printf("Error: Sorry try again.\n"
               "Please enter the column of your starting point.\n");
        int a;
        scanf("%i", &a);
        break;

        if(a=>1 && a<=3)
            printf("Please enter the row of your starting point.  Keep numbers in the range of one to three.\n");

        int b;
        scanf("%i", &b);
    }
}   

Answer 1

尽管您的程序是错误的，但错误消息意味着您必须在 if 语句的条件中将 =>= 替换为 >=

if(a=>1 && a<=3)

那是一定有

if(a >= 1 && a<=3)
     ^^^^

代码看起来像

#include <stdio.h>

int main( void )
{
    printf( "Welcome to the ROBOT GAME!\n"
            "To help you visualize draw a three by three board on a piece of paper.\n"
            "Please enter the column of your starting point.\n"
            "Keep numbers in the range of one to three.\n" );
    int a;

    scanf( "%i", &a );

    while ( a < 1 || a > 3 )
    {
        printf( "Error: Sorry try again.\n"
                "Please enter the column of your starting point.\n" );

        scanf( "%i", &a );
    }

    int b;

    printf( "Please enter the row of your starting point.  Keep numbers in the range of one to three.\n" );

    scanf( "%i", &b );

    while ( b < 1 || b > 3 )
    {
        printf( "Error: Sorry try again.\n"
                "Please enter the row of your starting point.\n" );

        scanf( "%i", &b );
    }

    return 0;
}