How can I call system when parameters (filenames, etc.) of the executed command arent known until run time?
How can I call system when parameters (filenames, etc.) of the executed command arent known until run time?
✍: Guest
Just use sprintf (or perhaps strcpy and strcat) to build the command string in a buffer, then call system with that buffer. (Make sure the buffer is allocated with enough space;
Here is a contrived example suggesting how you might build a data file, then sort it (assuming the existence of a sort utility, and Unix- or MS-DOS-style input/output redirection):
char *datafile = "file.dat";
char *sortedfile = "file.sort";
char cmdbuf[50];
FILE *fp = fopen(datafile, "w");
/* ...write to fp to build data file... */
fclose(fp);
sprintf(cmdbuf, "sort < %s > %s", datafile, sortedfile);
system(cmdbuf);
fp = fopen(sortedfile, "r");
/* ...now read sorted data from fp... */
2015-03-18, 1177👍, 0💬
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