To replace a certain string in a line

[hansoncry]

Hi everyone,

i met some difficulties handling the following problem. Say I have a input file in following format:
File Name File Number Size(blocks) Size(bytes)
file1 1 39 19968
file3 3 28 14336
file4 4 18 9216
file5 5 16 8192
file6 6 7 3584
file7 7 5 2560
file8 8 35 17920
file9 9 33 16896
file10 10 24 12288

My program suppose to simulate the rename operation on file.
For example, when u run "ren file1 file0", the input file will become as following:

File Name File Number Size(blocks) Size(bytes)
file0 1 39 19968
file3 3 28 14336
file4 4 18 9216
file5 5 16 8192
file6 6 7 3584
file7 7 5 2560
file8 8 35 17920
file9 9 33 16896
file10 10 24 12288

What I am able to do now is just insert the new file name "file0" in front of the old name in the input file,such as this:

File Name File Number Size(blocks) Size(bytes)
file0 file1 1 39 19968
file3 3 28 14336
file4 4 18 9216
file5 5 16 8192
file6 6 7 3584
file7 7 5 2560
file8 8 35 17920
file9 9 33 16896
file10 10 24 12288

so how can I delete the old file name? Any help would be greatly appreciated.

My current code is as following:

main(int argc, char **argv){
 
    FILE *list,*tmp;
    char line[80];
    char *pch;
 
 
    if(argc!=3){
        perror("You must have 2 argument.\n");
        exit(1);
    }
 
    //generate the tmp list file
    if((tmp = fopen("tmp.txt", "w+"))==NULL){
        printf("Cannot create temp list file");
    }
 
    //do the actual rename
    if(rename(argv[1], argv[2])) 
        printf("Rename failed.\n");
 
 
    //rename the entry in the table
    if((list = fopen("filelist.txt", "r+"))==NULL){
        printf("Cannot open the list file");
    }    
 
 
    while(fgets(line, sizeof(line), list))
    {
        printf("Line read: %s\n", line);
 
        if(strstr(line, argv[1]) !=NULL)
        {
            printf("Replacing.\n");
            strcpy(line, "");
            strcat(line, argv[2]);
        }
 
        fputs(line, tmp);
    }
 
 
    fclose(list);
    fclose(tmp);
 
    //remove filelist.txt
    if (remove("filelist.txt")){
            printf("Cannot delete file.\n");
            exit(1);
    }
 
    //rename tmp.txt to filelist.txt
    if(rename("tmp.txt", "filelist.txt")) 
        printf("Rename failed.\n");
 
}

[whodgson]

Maybe you could use the replace() function defined in the <algorithm> header and code s+4 to be replaced by "1" These functions are referred to as Standard C++ Generic Algorithms in a book i have read at least 19 times called Programming with C++ by John R Hubbard.