errno is a global variable in the C programming language that stores the error number of the last library function call. It is defined in the header file `<errno.h>`. For example:
c #include #include int main() { FILE *fp = fopen(“myfile.txt”, “r”); if (fp == NULL) { perror(“Error opening file”); return errno; } // Do something with the file fclose(fp); return 0; }
