如何只读取每行的第一个单词？ [英] How to read only the first word from each line?

问题描述

我做了很多简单的程序，但是我只是试图从文本文件的每一行读取第一个字到 char字符[30] 。

我试过了，但是没有成功。哦，我每次读它都必须重用这个字符。 （每次阅读时都要输入一个有序的列表）。

任何人都可以给我一种从文件中读取这种方式的方法，用简单的cleany

  FILE * fp; 
 char char [30]; 
 fp = fopen（/ myhome / Desktop / tp0_test.txt，r）; 
 if（fp == NULL）{
 printf（Erro ao abrir ficheiro！\\\
）; 
} else {
 while（！feof（fp））{
 fscanf（fp，％* [^ \\\
]％s，word）; //不能很好地工作... 
 printf（word read is：％s\\\
，word）; 
 strcpy（word，）; //它是否正确？ 
} 
} 
 fclose（fp）; 
  

例如，对于包含以下内容的文件：

  word1 word5 
 word2 kkk 
 word3 1322 
 word4 synsfsdfs 
  

只打印这个：

 读取的单词是：word2 
单词读取是：word3 
单词是：word4 
单词是：
  

解决方案

* [^ \\\
]％s，word）; //不能很好地工作...
fscanf（fp，％s％* [^ \\\
]，word）;

读取第一个单词并忽略其余部分，而不是忽略该行并读取第一个单词。 / p>

---

编辑一些解释

％s忽略空格，所以如果输入缓冲区有42，scanf会忽略第一个空格，将forty复制到目的地，并把缓冲区放在two之前的空格处。

％* [^ \\\
]会忽略换行符之前的所有内容，不包括换行符。因此，一个包含one \\\
two的缓冲区在scanf之后的换行符处被定位（就好像它是\\\
two）

I've done many simple procedures, but I'm only trying to read the first word into a char word[30], from each line of a text file.

I've tried, but without success. Oh, I have to reuse that char each time I read it. (To put in an ordered list each time I read it).

Can anyone show me a way to read this way from a file, in a simple and "cleany" way?

FILE *fp;
char word[30];
fp = fopen("/myhome/Desktop/tp0_test.txt", "r");
if (fp == NULL) {
    printf("Erro ao abrir ficheiro!\n");
} else {
    while (!feof(fp)) {
        fscanf(fp,"%*[^\n]%s",word);//not working very well...
        printf("word read is: %s\n", word);
        strcpy(word,""); //is this correct?
    }
}
fclose(fp);

For example for a file that contains:

word1 word5
word2 kkk
word3 1322
word4 synsfsdfs

it prints only this:

word read is: word2
word read is: word3
word read is: word4
word read is: 

解决方案

Just swap the conversion specifications in your format string

        // fscanf(fp,"%*[^\n]%s",word);//not working very well...
           fscanf(fp,"%s%*[^\n]",word);

Read the first word and ignore the rest, rather than ignore the line and read the first word.

---

Edit some explanation

%s ignores whitespace, so if the input buffer has " forty two", scanf ignores the first space, copies "forty" to the destination and leaves the buffer positioned at the space before "two"

%*[^\n] ignores everything up to a newline, excluding the newline. So a buffer containing "one \n two" gets positioned at the newline after the scanf (as if it was "\n two")

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