Question

我有一个文本文件text.txt，可以读取（为简单起见）

this is line one
this is line two
this is line three

为了简单起见，我只想将每行中的第一个字符设置为＆＃39; x＆＃39;，所以我想要的结果是

xhis is line one
xhis is line two
xhis is line three

所以我打开text.txt文件并尝试用所需的输出覆盖每一行到同一文本文件。在while循环中，我将每行中的第一个字符设置为＆＃39; x＆＃39;。我还设置变量＆＃34; line＆＃34;等于一，因为如果它在第一行，我想倒回到文件的开头，以便在开始时而不是在文件的末尾覆盖。然后增加行，以便在下一次迭代时跳过倒带，并且应该继续覆盖第2行和第3行。它适用于第一行。

有人有任何解决方案吗？顺便说一句，我已经在stackoverflow和其他网站上进行了广泛的研究，但没有运气。这是我的代码，我的输出也在下面：

#include <stdio.h>
#include <stdlib.h>
#define MAX 500

int main() {
    char *buffer = malloc(sizeof(char) * MAX);
    FILE *fp = fopen("text.txt", "r+");
    int line = 1;
    while (fgets(buffer, 500, fp) != NULL) {
            buffer[0] = 'x';
            if (line == 1) {
                    rewind(fp);
                    fprintf(fp, "%s", buffer);
            }
            else {
                    fprintf(fp, "%s", buffer);
            }
            line++;
    }
    free(buffer);
    fclose(fp);
}

输出：

xhis is line one
this is line two
xhis is line two
e
x

Answer 1

// Automatically load required Grunt tasks
require('jit-grunt')(grunt, {
  useminPrepare: 'grunt-usemin',
  ngtemplates: 'grunt-angular-templates',
  cdnify: 'grunt-google-cdn'
});

Answer 2

我总是建议使用另一个文件做这个kindda解决方案。

阅读
将x放入一行中的新文件中，然后复制该行的其余部分。
这样做直到你得到EOF
删除旧文件
重命名此新文件

Answer 3

试试这个

{{1}}

我在Windows上解决了这个问题

Answer 4

// file_overwrite.cpp : main project file.
// File opens and write y value to a file
// again reads same file and re-writes y value to a file

#include "stdafx.h"

using namespace System;

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

int main(int argc, char *argv[])
{
    int x = 19530;

    FILE *fp1 = fopen("D:\\Data\\BUFF.txt","w+");

    if(fp1 == NULL)
        printf("File not opening \n");
        int y=x;
        fprintf(fp1, "%d \n", y);
        fclose(fp1);
        printf("\n file -> open -> write y value and close");


        freopen("D:\\Data\\BUFF.txt", "w", fp1);
        rewind(fp1);
        y=100;
        fprintf(fp1, "%d \n", y);
        printf("\n file -> Reopen -> rewind write y values and close");
        fclose(fp1);

       getch();
       return 0;
}

Answer 5

// overwrite_file.cpp 
// File opens and write y value to a file
// again reads same file and re-writes y value to a file

#include "stdafx.h"

using namespace System;

#include<stdio.h>
#include<stdio.h>
#include<string.h>                //Include appropriate headers
#include <conio.h>
#include<stdlib.h>

int main(int argc, char *argv[])
{
    int x = 19530;                            // Give any value in the limit

    FILE *fp1 = fopen("D:\\Data\\BUFF.txt","w+");   // open file to write

    if(fp1 == NULL)                                 // if the file pointer encounters a null, it may not open neither overwrite 
        printf("File not opening \n");
        int y=x;                                     
        fprintf(fp1, "%d \n", y);                   //print y
        fclose(fp1);
        printf("\n file -> open -> write y value and close");  // close the file after writing the value of y


        freopen("D:\\Data\\BUFF.txt", "w", fp1);            //reopen and rewind file 
        rewind(fp1);
        y=100;                                              // this value of y given within the limits gets printed on the .exe console
        fprintf(fp1, "%d \n", y);
        printf("\n file -> Reopen -> rewind write y values and close");    // rewind write values and close 
        fclose(fp1);

       getch();
       return 0;
}

如何在C中读取和覆盖文本文件？

5 个答案: