[COD]: Verificar se string é valida

bool IsValidStr(char *schas){

    bool valid;

    valid = true;

    for (int i = 0; schas[i]; ++i){


        if ('a' <= schas[i] && schas[i] <= 'z' || 'A' <= schas[i] && schas[i] <= 'Z' || 47 < schas[i] && schas[i] < 58){
            continue;
        }
        else{
            valid = false;
        }
    }

    return valid;
}