Question

所以，我有这个：

将Order.txt

file.txt的; 10; 21：21

FILE2.TXT; 3; 20：00

FILE2.TXT; 30; 22：20

file4.txt; 3; 10：00

我希望用户提供所需的行（1到3，具体取决于存在多少行），然后更改其内容。例如：

第3行

“文件名： file.txt”

“秒： 5”

“时间HH：MM： 20:00”

输出/更改为order.txt：

file.txt的; 10; 21：21

FILE2.TXT; 3; 20：20

file.txt的; 5; 20：00

file4.txt; 3; 10：00

如您所见，第三行已更改。对于它，我尝试了以下内容：

变量

FILE* orderFile;
FILE* contentFile;
char fileName[50];
char timeValue[10];
int seconds;
char orderNameFile[50];
char orderTimeFile[50];
int orderSecondsFile;
int count = 0;
int i = 0;
int line;
int position;

代码

/* This will show the content on it with the number of the line behind */
orderFile = fopen("order.txt","r+");

printf("\n");

while(fscanf(orderFile," %49[^;];%d; %49[^\n]",fileName,&seconds,timeValue) == 3)
{
    i++;
    printf("[%d] %s;%d;%s\n",i,fileName,seconds,timeValue);
}

printf("\n");

rewind(orderFile);
/* ******************************************************************* */

/* This will ask which line he wants to change */
do{

    printf("Choose the line you want to change\n");
    printf("[Line] ");
    scanf("%d",&line);
    printf("\n");

    if(line > i)
    {
         printf("That line does not exist\n\n");
    }

}while(line > i || line < 1);
/* ******************************************* */

/* This will ask for the file name, seconds and time in HH:MM */
printf("Insert the name of the file\n");
printf("[Name] ");
getchar();
scanf("%s",&orderNameFile);

printf("Insert the presentation time in seconds\n");
printf("[Time in seconds] ");
scanf("%d",&orderSecondsFile);

printf("Insert the hour it starts\n");
printf("[Time in HH:MM (Hour:Minutes)] ");
getchar();
scanf("%s%",&orderTimeFile);
/* ******************************************* */

/* This is what is supposed to edit the line I want but does not work */
while(fscanf(orderFile," %49[^;];%d; %49[^\n]",fileName,&seconds,timeValue) == 3)
{
    count++;

    if(count == line)
    {
        position = ftell(orderFile);
        fseek(orderFile, position, SEEK_SET);
        fprintf(orderFile,"%s;%d;%s",orderNameFile,orderSecondsFile,orderTimeFile);
        break;
    }
}
*/ ****************************************************************** */

fclose(orderFile);

输出我想使用第一个例子：

file.txt的; 10; 21：21

FILE2.TXT; 3; 20：20

file.txt的; 5; 20：00

file4.txt; 3; 10：00

输出它让我使用第一个例子@EDITED：

file.txt的; 10; 21：21

FILE2.TXT; 3; 20：00

FILE2.TXT; 30; 22：20file.txt; 5; 20：00

file4.txt; 3; 10：00

关于它可能是什么的任何想法？

Answer 1

通常可以更好地写入临时文件，然后删除原始文件并将临时文件重命名为原始文件的名称

FILE *temp = fopen ( "temp", "w");
/* This is what is supposed to edit the line I want but does not work */
while(fscanf(orderFile," %49[^;];%d; %49[^\n]",fileName,&seconds,timeValue) == 3)
{
    count++;

    if(count == line)
    {
        fprintf(temp,"%s;%d;%s\n",orderNameFile,orderSecondsFile,orderTimeFile);
    }
    else 
    {
        fprintf(temp,"%s;%d;%s\n",filename,seconds,timeValue);
    }
}
fclose ( temp);
fclose ( orderFile);
remove ( "order.txt");// comment these two lines out until you are sure temp is correct
rename ( "temp", "order.txt");//that way you do not loose the original file

Answer 2

你必须存储这些行，然后将它们重写到文件中，可能会有更优雅/高效的解决方案，但对于一个简单的情况，这应该没问题，这里是代码

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

int main()
{
    FILE* orderFile;
    char fileName[50];
    char timeValue[10];
    int seconds;
    char orderNameFile[50];
    char orderTimeFile[50];
    int orderSecondsFile;
    int count;
    int lineCount;
    int line;
    char lineContent[128];
    char fileLines[128][128];

    /* This will show the content on it with the number of the line behind */
    orderFile = fopen("order.txt", "r+");
    if (orderFile == NULL)
        return -1;
    lineCount = 0;

    while ((fgets(lineContent, sizeof(lineContent), orderFile) != NULL) && (lineCount < 128))
    {
        size_t length;

        length = strlen(lineContent);
        if (lineContent[length - 1] == '\n')
            lineContent[length - 1] = 0;
        if (sscanf(lineContent, " %49[^;];%d; %49[^\n]", fileName, &seconds, timeValue) == 3)
        {
            strcpy(fileLines[lineCount], lineContent);
            printf("[%d] %s;%d;%s\n", ++lineCount, fileName, seconds, timeValue);
        }
    }
    printf("\n");

    rewind(orderFile);

    /* This will ask which line he wants to change */
    do {

        printf("Choose the line you want to change\n");
        printf("[Line] > ");

        scanf("%d", &line);

        if ((line > lineCount) || (line < 1))
             printf("That line does not exist\n\n");
    } while ((line > lineCount) || (line < 1));

    /* This will ask for the file name, seconds and time in HH:MM */
    printf("Insert the name of the file\n");
    printf("[Name] ");

    scanf("%49s", orderNameFile);

    printf("Insert the presentation time in seconds\n");
    printf("[Time in seconds] ");

    scanf("%d", &orderSecondsFile);

    printf("Insert the hour it starts\n");
    printf("[Time in HH:MM (Hour:Minutes)] ");

    scanf("%49s", orderTimeFile);

    /* This is what is supposed to edit the line I want but does not work */
    count = 0;
    while (++count < lineCount + 1)
    {
        if (count == line)
            fprintf(orderFile, "%s;%d;%s\n", orderNameFile, orderSecondsFile, orderTimeFile);
        else
            fprintf(orderFile, "%s\n", fileLines[count - 1]);
    }
    fclose(orderFile);

    return 0;
}

Answer 3

删除文件内容是一项代价高昂的操作，处理此问题的更好方法是

使用写入模式
开始将以前文件的内容写入此新文件。
一旦到达应更换的行，请确保忽略读取行并使用fprintf()

IMO这是更容易和正确的方法。使用以下线程作为参考

Delete a Line from a file in C Language

检查行，然后在txt文件上更改其数据

3 个答案: