c - 逐字读取文件并输出空格

Question

输入的文本文件是这样的:

Hello my
name is 
mark.
and
im 
going
to
love
c!

代码:

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

 int main(int argc, char *argv[]){
FILE *pFile;
char x[60];

pFile = fopen("test0.txt","r");

if(pFile != NULL){
    while(fscanf(pFile, " %60s", x) == 1){
        printf("%s",x);
 }

}
}

输出文本文件为:

Hellomynameismark.andimgoingtolovec!

我希望输出如下:

Hello my name is mark. and im going to love c!

非常新的 C 程序员，所以只知道基础知识。

编辑----

   int main(int argc, char *argv[]){
FILE *pFile;
char x[60],line[60];

pFile = fopen("test0.txt","r");

while(!feof(pFile)){

        fgets(line, 60, pFile);
        strtok(line, "\r\n");
        printf("%s", line );
    }
    fclose(pFile);

输出:

 Hello myname is mark.andim goingtolovec!

这不会在新行之间留下空格。但是，如果我取出 strtok 行，输出将是这样的:

Hello my
name is 
mark.
and
im 
going
to
love
c!

--编辑

 .sp 2
 .ce
 This is an example file for formatting.
 .sp 1
 The above line
 was formatted using a .ce 1 command, which means 'centre
 the following line',
 so it should appear in the 
 centre of the page.
 The paragraph was separated from the heading using
 a .sp 1 command to create a single blank line.
 There should also be two blank lines above the centred heading to make            reading it slightly easier.

Answer 1

简单的答案是:

while(fscanf(pFile, " %59[^\n]%*c", x) == 1)

这里 %[^\n] 使用字符类 [stuff] 读取所有内容直到换行符。 %*c 只是读取并丢弃换行符，而不将其添加到 fscanf 的匹配计数中。

但是对于面向行的输入，您应该真正使用标准库提供的面向行函数之一(例如fgets或 POSIX getline)。

使用 fgets 和 strtok

正如您从评论中了解到的那样，feof 的使用只会让您感到悲伤。您将只想使用 fgets 的返回来确定文件结尾。这是一个将拼图的所有部分放在一起的示例:

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

#define MAXWDS  20
#define MAXCHR  60

int main (int argc, char **argv) {

    char line[MAXCHR] = {0};
    char *words[MAXWDS] = {NULL};
    FILE *pFile = NULL;
    size_t i, index = 0;

    /* open file for reading (if provided), or read from stdin */    
    if (!(pFile = argc > 1 ? fopen (argv[1], "r") : stdin)) {
        fprintf (stderr, "error: file open failed '%s'.\n", argv[1]);
        return 1;
    }

    while (fgets (line, 60, pFile)) 
    {
        char *p = line;

        /* split line into tokens, stored in words[] */
        for (p = strtok (p, " \r\n"); p; p = strtok (NULL, " \r\n")) {
            words[index++] = strdup (p); /* allocate & copy */

            if (index == MAXWDS)    /* check pointer limit */
                break;
        }

    }
    if (pFile != stdin) fclose (pFile);

    /* output in a single line */
    for (i = 0; i < index; i++) {
        printf (" %s", words[i]);
        free (words[i]);            /* free allocated memory */
    }

    putchar ('\n');

    return 0;
}

编译

gcc -Wall -Wextra -o bin/fgets_strtok fgets_strtok.c 

输出

$ ./bin/fgets_strtok dat/hellomark.txt
 Hello my name is mark. and im going to love c!

注意:简单地打印出单词之间有空格的行，只要每行中的每个单词之间已经有一个空格，就没有理由去麻烦要将每一行分成单独的单词，您可以简单地以空格分隔的方式打印出每一行的内容。您在使用 fgets 时遇到的唯一问题是它还会读取 newline(或 carriage return, newline)作为字符串的一部分。这很容易删除。您可以将整个读取循环替换为:

while (fgets (line, 60, pFile)) 
{
    size_t len = strlen (line);

    /* strip trailing newline (or carriage return newline ) */
    while (len && (line[len-1] == '\n' || line[len-1] == '\r'))
        line[--len] = 0;  /* overwrite with null-terminating char */

    words[index++] = strdup (line); /* allocate & copy */

    if (index == MAXWDS)    /* check pointer limit */
        break;
}

输出

$ ./bin/fgets_mark <dat/hellomark.txt
 Hello my name is mark. and im going to love c!

仅从文件(不是文件或标准输入)读取的标准方法

我很抱歉让您有点超前，包括打开文件(如果在命令行上提供)或从 stdin 读取(如果未提供文件名)的方法。标准方法是首先检查命令行上提供的参数数量是否正确，然后打开提供的文件名，验证它是否打开，然后处理输入。我所做的是将 三元运算符 放入 fopen 命令中。

pFile = argc > 1 ? fopen (argv[1], "r") : stdin

'=' 符号的右边是一个三元运算符，它只是if -> then -> else 的简写。它的作用是询问 argc > 1？如果测试 true，则 pFile = fopen (argv[1], "r");。如果 argc > 1 测试 false，则 pFile = stdin;

看看标准方式是否更有意义:

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

#define MAXWDS  20
#define MAXCHR  60

int main (int argc, char **argv) {

    char line[MAXCHR] = {0};
    char *words[MAXWDS] = {NULL};
    FILE *pFile = NULL;
    size_t i, index = 0;

    /* validate sufficient input */
    if (argc < 2 ) {
        fprintf (stderr, "error: insufficient input, usage: %s filename\n", argv[0]);
        return 1;
    }

    /* open file provided on command line for reading */
    pFile = fopen (argv[1], "r");
    if (!pFile) {
        fprintf (stderr, "error: file open failed '%s'.\n", argv[1]);
        return 1;
    }

    while (fgets (line, 60, pFile)) /* read each line in file */
    {
        size_t len = strlen (line);

        /* strip trailing newline (or carriage return newline ) */
        while (len && (line[len-1] == '\n' || line[len-1] == '\r'))
            line[--len] = 0;  /* overwrite with null-terminating char */

        words[index++] = strdup (line); /* allocate & copy */

        if (index == MAXWDS)    /* check pointer limit */
            break;
    }
    if (pFile != stdin) fclose (pFile);

    /* output in a single line */
    for (i = 0; i < index; i++) {
        printf (" %s", words[i]);
        free (words[i]);            /* free allocated memory */
    }

    putchar ('\n');

    return 0;
}