在C中的可执行目录中设置文件名

Question

I have to create a buffer to hold the the name of a license file which is in the executable directory. This is my solution (I'm not a C programmer):

char buffer[MAX_PATH] = "";
GetModuleFileName(NULL, buffer, MAX_PATH);
int len = (int) strlen(buffer);
buffer[len-7] = '\0';
strcat(buffer,"license.lic");

Note I know the name of the executable is net.exe - 7 chars, so I'm cheating.

Firstly is this code safe? I got a compiler warning about using strcat saying I should use strcat_s, but I couldn't get that working.

Secondly how do I get the correct length of the executable name?

Answer 1

Your code is reasonably safe. Assuming MAX_PATH is the maximum possible length of a pathname, replacing the executable name with license.lic should fit in that size.

Rather than getting the length of the executable name, you can search for the last directory delimiter character, and copy license.lic after it. C has a built-in function strrchr() for searching a string in reverse.

char *sepptr = strrchr(buffer, '\\');
if (sepptr == NULL) {
    sepptr = buffer; // no directory delimiter, replace it completely
} else {
    sepptr++; // point to just past the delimiter
}
strcpy(sepptr, "license.lic"); // Overwrite executable name with license name