将简单循环转换为 do-while

Question

我将如何转换以下 while循环到正确的 do-while第一次没有重复计算？

void ctype()
{
    char c;
    while ((c = getchar()) != '.')
        printf("'%c' is %s a letter.\n", c, isalpha(c)? "indeed" : "not");
    printf("'%c' is %s a letter.\n", c, isalpha(c)? "indeed" : "not");
}

到目前为止我所拥有的是:

void ctype()
// Print the letters up through the period, but quit on the period
{
    char c = getchar();
    do {
        printf("'%c' is %s a letter.\n", c, isalpha(c)? "indeed" : "not");
    } while ((c = getchar()) != '.') 
}

但是这个双- getchar是第一项。这样做的正确方法是什么？这几乎就像我想要在 getchar() 上的等价的后增量在while循环中。
while 的示例输入/输出循环，目前是正确的:

$ run
.
'.' is not a letter.
$ run
Hello.
'H' is indeed a letter.
'e' is indeed a letter.
'l' is indeed a letter.
'l' is indeed a letter.
'o' is indeed a letter.
'.' is not a letter.

Answer 1

可以这样做:

char c;
do {
    c = getchar();
    printf("'%c' is %s a letter.\n", c, isalpha(c)? "indeed" : "not");
} while(c != '.');

在一般情况下，您可以随时更改

while(<expr>) {
    // Body
}

到

do {
    if(<expr>) break;

    // Body
} while(1);

请注意，这仅用于简单地转换为 do-while。代码中还有其他缺陷。同时纠正这些:

int c;
do {
    c = getchar();
    if(c == EOF) break;
    printf("'%c' is %s a letter.\n", c, isalpha(c)? "indeed" : "not");
} while(c != '.');