I'm trying to open different files by having a for loop increment a counter, then appending that counter to the filename to be opened, but I'm stuck on how to use strcat to do this. If I understand right, strcat takes 2 strings, but my counter is an int. How can I make it so that it becomes a string?
for(a = 1; a < 58; a++) {
FILE* inFile;
int i;
char filename[81];
strcpy(filename, "./speeches/speech");
strcat(filename, a);
strcat(filename, ".txt");
Definitely doesn't work since a is an int. When I try casting it to char, because a starts at 1 and goes to 57, I get all the wrong values since a char at 1 is not actually the number 1.. I'm stuck.
You can't cast an integer into a string, that's just not possible in C.
You need to use an explicit formatting function to construct the string from the integer. My favorite is snprintf()
.
Once you realize that, you can just as well format the entire filename in a single call, and do away with the need to use strcat()
(which is rather bad, performance-wise) at all:
snprintf(filename, sizeof filename, "./speeches/speech%d", a);
will create a string in filename
constructed from appending the decimal representation of the integer a
to the string. Just as with printf()
, the %d
in the formatting string tells snprintf()
where the number is to be inserted. You can use e.g. %03d
to get zero-padded three-digits formatting, and so on. It's very powerful.