C程序在txt文件中添加编号

Question

我有一个文本文件名myData.txt 它包含以下文本：

Bob Smith 5555556666
Wei Song 5555554444
George Snufolopolous 5555556666
William Kidd 5555554444
Hopalong Cassidy 5555556666
Lone Ranger 5555554444
Tonto Ng 5555556666
Pancho Vilas 5555554444
Cisco Kid 5555559999

我想将文件 myData.txt 的文本更改为以下内容：

1 Bob Smith 5555556666
2 Wei Song 5555554444
3 George Snufolopolous 5555556666
4 William Kidd 5555554444
5 Hopalong Cassidy 5555556666
6 Lone Ranger 5555554444
7 Tonto Ng 5555556666
8 Pancho Vilas 5555554444

我使用的代码是C语言的，是：

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#define MAXSIZE 8
struct Record
{

    int id;

    char firstName[31];

    char lastName[31];

    char cellPhone[11];
};

int main(void)
{
    struct Record record[MAXSIZE];
    int numberOfRecords = 0;
    FILE *fp = NULL;
    int i = 0;
    fp = fopen("myData.txt", "w");
    if (fp == NULL)
    {

        while (fscanf(fp, "%s %s %s", record[i].firstName,

                      record[i].lastName, record[i].cellPhone)

                   != EOF &&
               i < MAXSIZE)

        {

            record[i].id = i + 1;

            numberOfRecords++;

            i++;
        }
    }

    fp = fopen("myData.txt", "a");

    if (fp == NULL)

    {

        for (i = 0; i < numberOfRecords; i++)

        {

            fprintf(fp, "%d%s%s%s\n", record[i].id, record[i].firstName,

                    record[i].lastName, record[i].cellPhone);
        }
    }

    return 0;
}

当我编译这段代码时，文件 myData.txt 变空了。这段代码有什么问题，请评论link到可能能够解决问题的资源。

Answer 1

首先要做的事：您应该总是在再次打开文件之前先关闭它。打开一个文件两次而不关闭它可能会损坏文件并且您会丢失数据。

其次你可以这样做：

1. use argc and argv to take myData.txt as command-line input
2. open myData.txt and one another file and
3. using fread() read each object in a struct Record's object and 
   write it to another file using fprintf(fp, "%i %s %s %s", i + 1, ... );
4. repeat 3 until total number of objects are read or EOF is reached.
5. CLOSE both files and return

这里 struct Record 就像：

struct Record
{
    char firstName[31];

    char lastName[31];

    char cellPhone[11];
};

C程序在txt文件中添加编号

C program to add numbering in txt file

c

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fopen

struct

record