在sscanf（）中读取可选的空格

So i have been working on an C project and im stuck on this problem, basically Im making a program where the user can enter their name and I later print it out to a file, the first and last name of the user is split with a comma however, optional whitespace in around the comma is allowed. This is what i have been using the read the user names:

所以我一直在研究一个C项目并且我坚持这个问题,基本上我正在创建一个程序,用户可以输入他们的名字,然后我将它打印到一个文件,用户的名字和姓氏被分成一个但是,逗号周围的可选空格是允许的。这就是我一直在使用的读取用户名:

    char lastName[20]; 
    char firstName[20]; 
    char line[LINESIZE]; 
    while(fgets(line,LINESIZE,stdin)) { 
       if((sscanf(line," %s , %s ",lastName,firstName)) == 2)  { 
             /*process name */
       } 
    }

However, the only time it reads input successfully is when the user inputs:

但是,它成功读取输入的唯一时间是用户输入:

john , doe

which matches the %s , %s I have, how can i make it such that something like:

哪个匹配%s,%s我有,我怎么能这样做,像:

john, doe 
john ,doe

Can all work?

一切都可以吗?

I have also tried

我也试过了

sscanf(line,"%s%[],%[]%s");

This doesnt cause compilation error, but it doesnt process input meaning it doesnt match the %s , %s

这不会导致编译错误,但它不会处理输入,这意味着它与%s,%s不匹配

2 个解决方案

#1

This will isolate the names so that any permutation of "Doe , John" filters out the whitespace

这将隔离名称,以便“Doe,John”的任何排列过滤掉空白

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

#define LINESIZE 100

int main(void) {
    char lastName[20] = {0}; 
    char firstName[20] = {0}; 
    char line[LINESIZE]; 
    char *first = NULL, *last = NULL;
    if (NULL == fgets(line,LINESIZE,stdin))
        return 1;
    last = strtok (line, ", \t\r\n");
    if (last)
        first = strtok (NULL, ", \t\r\n");

    if (last && first) {
        sprintf(firstName, "%.19s", first);
        sprintf(lastName, "%.19s", last);
        printf ("%s %s\n", firstName, lastName);
    }
    return 0;
}

#2

You can modify the sscanf format to have it perform a more stringent test:

您可以修改sscanf格式以使其执行更严格的测试:

char eol[2];
if (sscanf(line, " %19[a-zA-Z-] , %19[a-zA-Z-]%1[\n]", lastName, firstName, eol) == 3) ...

sscanf will verify that the user typed exactly 2 words made of letters separated by a comma and optional spaces and followed by a line feed.

sscanf将验证用户是否正好键入了由逗号和可选空格分隔的字母组成的2个单词,后跟换行符。

But I strongly encourage you to parse the input yourself instead of relying on sscanf. It is not difficult, much more precise and flexible, and less error prone:

但我强烈建议您自己解析输入,而不是依赖于sscanf。它不难,更精确,更灵活,更不容易出错:

char lastName[LINESIZE];
char firstName[LINESIZE]; 
char line[LINESIZE]; 
while(fgets(line,LINESIZE,stdin)) {
   char *p = line, *q;
   while (isspace((unsigned char)*p)) p++;
   for (q = lastName; isalpha((unsigned char)*p); p++) {
       *q++ = *p;
   }
   *q = '\0';
   while (isspace((unsigned char)*p)) p++;
   if (*p == ',') p++;
   while (isspace((unsigned char)*p)) p++;
   for (q = firstName; isalpha((unsigned char)*p); p++) {
       *q++ = *p;
   }
   *q = '\0';
   while (isspace((unsigned char)*p)) p++;
   if (*lastName && *firstName && !*p) {
       // format is OK
       printf("Hello %s %s\n", firstName, lastName);
   } 
}

#1