Trying to create file in directory in C, but file is not being created

Question

I have been searching for hours and hours now and cannot figure out why this is not working. I want to create a file in C, in a directory I created, but the file is not being created. Here is the relevant code pertaining to making the directory and creating the file.

#include<sys/types.h> #include<sys/stat.h> #include<fcntl.h> #include<stdio.h> #include<unistd.h> #include<stdlib.h> #include<string.h> #include<time.h> #include<assert.h> char d1[50] = "myname.rooms."; char str[50]; char filename[50]; int d2 = getpid(); int dir; const char *rooms[10] = {"Lillard", "Matthews", "Batum", "Aldridge", "Lopez", "Mccollum", "Leonard", "Blake", "Gee", "Freeland"}; int z; sprintf(str, "%i", d2); strcat(d1, str); dir = mkdir(d1, S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH); snprintf(filename, 50, "/%s/%s.txt", d1, rooms[0]); z = strlen(filename); for(i=0; i<z; i++) { str[i] = filename[i]; } FILE *f; f = fopen("str", "w+"); fprintf(f, "ROOM NAME: %s\n", (rooms[0])); fclose(f);

Making the directory works, there is just no file created in that directory or anywhere else. I want to loop through and create files for each of those rooms, but I just wanted to get it to function with 1 first. I printed out the str string and it came out as /myname.rooms.22222/Lillard.txt where myname.rooms.22222 is the directory and Lillard.txt should be the file name. I am stuck right now, please help.

You're not checking the return values of the system calls, so you won't ever know why your program fails. Do that. Then look at your fopen call and tell us what filename it could possibly create (and in which directory). — Mat
– Mat, Commented May 10, 2015 at 16:15
The return value of f is 0, which seems it would indicate a null pointer or a failure to create or open the file. — Shaine
– Shaine, Commented May 10, 2015 at 16:56

Nikolai Fetissov · Accepted Answer · 2015-05-10 16:47:35Z

2

You are creating the file with literal name "str" in the current directory where you run the program.

Do something like this:

char dir_name[PATH_MAX]; mode_t dir_mode = ...; /* your file mode bits */ int i = ...; /* your value */ snprintf( dir_name, PATH_MAX, "whatever.%d", i ); if ( mkdir( dir_name, dir_mode ) == -1 ) { if ( errno != EEXIST ) err( 1, "mkdir" ); } if ( chdir( dir_name ) == -1 ) err( 1, "chdir" ); char file_name[FILENAME_MAX]; snprintf( file_name, FILENAME_MAX, "%s.txt", whatever ); FILE* fp = fopen( file_name, "w+" ); if ( fp == NULL ) err( 1, "fopen" ); /* now you have the file open for writing */ ... fclose( fp );

edited May 10, 2015 at 16:47

answered May 10, 2015 at 16:16

Nikolai Fetissov

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5 Comments

Shaine Over a year ago

Sorry, that happened in the process of trying out a lot of things to troubleshoot. If I take off the quotes I get a seg fault. After checking the return value of f it returns 0.

Nikolai Fetissov Over a year ago

You don't need that str variable at all, just use the string with the formatted file name.

Shaine Over a year ago

I tried just using my filename value in there as well and it still seg faulted. I will try out the code you provided.

Shaine Over a year ago

I tried this out and it keeps saying fopen: No such file or directory. I know the directory exists because I can find it and open it in Linux, so there is obviously something going wrong with the file creation.

Shaine Over a year ago

Nevermind, I was able to get it to work. Thank you very much for your help.

fassl · Accepted Answer · 2015-05-10 16:23:48Z

In this code the file should be called "str" (is this intended for testing or did you actually want to use contents of str variable?

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