/in/lab5.c: In function 'evaluatePostfix':
/in/lab5.c:115:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < strlen(postfix); i++) {
                       ^
/in/lab5.c:121:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             while (i < strlen(postfix) && (isdigit2(postfix[i]) || postfix[i] == '.' || postfix[i] == '-')) {
                      ^