check lowercase letters c 2b 2b

1for(int i=0;i<str.size();i++){
2int c = str[i]; 
3        if (islower(c))  
4            str[i] = toupper(c);
5}

1if (isupper(str[i])) {
2	// str[i] is uppercase
3}

1str[i] = toupper(str[i]);

1str[i] = tolower(str[i]);

1char character = 'a'; //0110 0001
2if(character & 0x20) {
3	//is lowercase
4}