/in/lab5.c: In function 'evaluatePostfix':
/in/lab5.c:165:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < strlen(postfix); i++) {
                       ^
/in/lab5.c:171:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             while (i < strlen(postfix) && (isdigit2(postfix[i]) || postfix[i] == '.' || postfix[i] == '-')) {
                      ^
/in/lab5.c: In function 'replaceVariables':
/in/lab5.c:276:54: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
             if (i == len - 1 || !(expr[i + 1] >= 'A' && expr[i + 1] <= 'Z' || expr[i + 1] >= 'a' && expr[i + 1] <= 'z' || expr[i + 1] >= '0' && expr[i + 1] <= '9')) {
                                   ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
/in/lab5.c:276:142: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
             if (i == len - 1 || !(expr[i + 1] >= 'A' && expr[i + 1] <= 'Z' || expr[i + 1] >= 'a' && expr[i + 1] <= 'z' || expr[i + 1] >= '0' && expr[i + 1] <= '9')) {
                                                                                                                           ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~