C 程序读取/写入文件，同时递增文件中的数字

Question

我正在从文件中读取时间，然后尝试将读取时间转换为秒。有没有更简单的方法来转换时间戳？我的方法似乎效率很低。您建议写入文件时最好的方法是什么？

示例文件

My test file
00:19.1 123456
00:35.4 testing whitespace end

Desired Output
1: My test file
2: 00:19.1
3: 00:35.4

代码:

#include <stdio.h>

#define MAXC 1024                                                                   // define constants, don't use magic number in code
#define MAXN 40
int main (int argc, char **argv) {

    char buf[MAXC] = "";                                                            // buffer to hold each line -- size as reqd
    char filename[MAXN];
    int line = 1;
    int replace_line;
    FILE *fp, *fp2;
    printf("Please enter a file name: ");
    scanf("%s",&filename);
    fp = fopen(filename,"r+");
    if (!fp)                                                                        // validate file open for reading
    {
        fprintf (stderr, "error: file open failed '%s'.\n", argv[1]);
        return 1;
    }
    //printf("Enter a increment of time: ");
    //scanf("%d", &increment);
    while (fgets (buf, sizeof buf, fp))                                             // read each line in file
    {
        char et[MAXC] = "";                                                         // buffer for holding time
        char etR[MAXC] = "";
        char time[7] = "";
        int filler = 0;

        if (line == 1)                                                              // if 1st line, just print
        {
            printf ("%d : %s", line, buf);                                          // note: \n included by fgets
            //fprintf(fp2,"%s",buf);
        }   // end of if first line
        else
        {
            if (sscanf (buf, "%s", et) != 1)                                        // parse up to first whitespace
            {
                fprintf (stderr, "error: invalid conversion, line %d\n", line);
                return 1;
            }
            printf ("%d : %s\n", line, et);                                         //output elapsed time only
            while(filler < 7)
            {
                time[filler] = et[filler];
                filler++;
            }
            time[1] = time[1] - '0';    //Leading Minute (error if over 6)
            time[2] = time[2] - '0';    //Minute
            time[4] = time[4] - '0';    //Leading Second (Add to minute if over 6)
            time[5] = time[5] - '0';    //Second (Add to LS if over 9)
            time[7] = time[7] - '0';    //fraction of a second (Add to S if over 9)
            float timeInSeconds;
            char minuteHolder[2];
            sprintf(minuteHolder,"%d%d",time[1],time[2]);
            int minute;
            minute = (minuteHolder[0]*10) + minuteHolder[1];
            printf("\n%d\n",minute);
            //getting 539 , minutes on every line???

        }   //end of else
        line++;                                                                     // increment line count
    }   // end of while parsing file
    rewind(fp);
    if (fp != stdin)                                                                // close file if not stdin
    {
        fclose (fp);
    }
    return 0;
}

Answer 1

转换源字符串:“00:19.1 123456”目标字符串: "1.00:19.1"

• 第一个:我们应该找到黑色字符 pos:
  *char pblack = strchr(buf, ' ');
  现在pblack指向“123456”。
• 第二:我们将旧字符串设置为新字符串:
  因为字符串以 '\0' 结尾，
  所以我们设置:pblack[0] = '\0';

现在，我们有了代码:

#include <stdio.h>

#define MAXC 1024                                                                   // define constants, don't use magic number in code
#define MAXN 40
int main(int argc, char **argv) {

char buf[MAXC] = "";                                                            // buffer to hold each line -- size as reqd
char filename[MAXN];
int line = 1;
int replace_line;
//FILE *fp = argc > 1 ? fopen (argv[1], "r") : stdin;
//FILE *fp = fopen("test.txt","r");
FILE *fp, *fp2;
printf("Please enter a file name: ");
scanf("%s", &filename);
fp = fopen(filename, "r+");
//fp2 = fopen("datadump.txt","w");
if (!fp)                                                                        // validate file open for reading
{
    fprintf(stderr, "error: file open failed '%s'.\n", argv[1]);
    return 1;
}
//printf("Enter a increment of time: ");
//scanf("%d", &increment);
while (fgets(buf, sizeof buf, fp))                                             // read each line in file
{
    char et[MAXC] = "";                                                         // buffer for holding time
    char etR[MAXC] = "";
    char time[7] = "";
    int filler = 0;

    if (line == 1)                                                              // if 1st line, just print
    {
        printf("%d : %s", line, buf);                                          // note: \n included by fgets
                                                                               //fprintf(fp2,"%s",buf);
    }   // end of if first line
    else
    {
        char *pblack = strchr(buf, ' '); // get chr ' ' pos
        pblack[0] = 0;                   // set ' ' to '\0', get the new string 
        printf("%d : %s\n", line, buf);
    }   //end of else
    line++;                                                                     // increment line count
}   // end of while parsing file
rewind(fp);
//fp2 = fopen("replica.c","w");
//replacement code
/*
flcose(fp);
fclose(fp2);
remove(filename(;
rename("replica.c",filename);
//if you to show them new file fflush stdin and repeat while
//fp = fopen(filename, "r");
//while loop
*/
if (fp != stdin)                                                                // close file if not stdin
{
    fclose(fp);
    //fclose (fp2);
}
return 0;

}