So I'm trying to get this program that will say good or bad depending on your answer and I didn't want to have a really long if and else if statement with a bunch of strings so I put a bunch of possible answers in two chars and I want it to answer depending on what you say. The program only replies to the good answers saying good even if you enter in one of the bad answers.
const char* good[5] = {
"good", "great", "amazing", "amazing!", "fantastic"
};
const char* bad[5] = {
"bad", "bad pal", "bad eugene", "not good", "not good pal"
};
string input01 = "";
int main() {
cout << "Hello" << endl;
system("PAUSE");
system("CLS");
cout << "How are you doing today?" << endl;
cin >> input01;
transform(input01.begin(), input01.end(), input01.begin(), ::tolower);
if (input01 == good[0 > 5] || good[0 < 5]){
system("CLS");
cout << "good" << endl;
system("pause");
}
else if (input01 == bad[0 > 5] || bad[0 < 5]){
system("CLS");
cout << "bad" << endl;
system("pause");
}
}
This: if (input01 == good[0 > 5] || good[0 < 5]) probably doesn't do what you expect (because I can't imagine wanting what it really does).
0 > 5 is evaluated as a test of whether 0 is greater than 5. Since it's obviously not, that produces false. Since it's being used in a context where an integer is needed, that's converted to 0, so that part of the expression becomes if (input01 == good[0].
Likewise, 0 < 5 tests whether 0 is less than 5 (which it obviously is) so the result is true, which converts to 1, so that part of the expression is good[1]. Since that in turn is being used as a Boolean expression, it's treated as equivalent to good[1] != 0.
So what you have overall is if (input01 == good[0] || good[1] != 0).
That seems close enough to useless that I'm pretty sure it's not what you wanted. In particular, good[1] is a pointer. A pointer will compare equal to 0 if and only if it's a null pointer. Since it's initialized to point at something, it's not a null pointer, so that part of the expression will always evaluated as true.
of course, your other if statement is about equally useless.
If you want to check whether input01 is equal to any of the items in good, you might (for one example) use std::find:
if (std::find(std::begin(good), std::end(good), input01) == std::end(good))
// input01 was not present in `good`.
To make that work correctly, you'll want to use std::strings though:
std::vector<std::string> good{"good", "great", "amazing", "amazing!", "fantastic"};
It's kind of pointless for only 5 items, but if you lists of good and bad words are likely to get really large, you'd probably be better off sorting them, then using std::binary_search, or else using std::unordered_set instead.
Try:
if ((strcmp(input.c_str(), good[0]) == 0) ||
(strcmp(input.c_str(), good[1]) == 0) ||
...
(strcmp(input.c_str(), good[4]) == 0))
Or better switch the keywords to strings,
const string good[5] = {
"good", "great", "amazing", "amazing!", "fantastic"
};
and then
if ((input == good[0]) ||
(input == good[1]) ||
...
(input == good[4]))
Or even better, pack the keywords into a set
const set<string> good{"good", "great", "amazing", "amazing!", "fantastic"};
and then
if (good.find(input) != good.end())
Why don't you just check if the input01 is in your array. You should be able to use the find() function to do this. Something like
if(std::find(std::begin(good), std::end(good), input01) != std::end(good))){do something}
You may not need the std:: references
Related
I am having issues with this block of code:
else if (mineOrRefine == "refine" || mineOrRefine == "Refine")
if (StoneInventory[0] == 0)
cout << "You currently have no stone!" << endl;
int a = StoneInventory[0];
else if (a == >1)
You're not saying what the problem is, but I can all but guarantee it has to do with a lack of braces. Put your if and else blocks into braces, even when it's just one line, to reduce confusion. I'm not going to get into a debate about whether to put braces around a single expression following if/else in general, only that, in your case, the lack of braces is confusing you, so put them in.
instead of ( a== >1), use (a>=1) or (a>0)
also, any 'if' statement with more than one line of code should use curly braces. ie: if (x) { /* code */ }.
You're lost in the ifs, and you really need to add curly braces to see what's going on. The code amounts to this:
if (something_you_havent_shown)
{
// something else you haven't shown
}
else if (mineOrRefine == "refine" || mineOrRefine == "Refine)
{
if (StoneInventory[0] == 0)
{
std::cout << "You currently have no stone!" << std::endl;
}
}
int a = StoneInventory[0];
else if (something_you_say_youve_changed_since_asking_the_question)
The else in that last line doesn't go with any preceding if -- they've all finished, because each one applies only to the next line.
Every time I run this code, for whatever reason, it calls all functions regardless of whether the if statement evaluates to true
int main()
{
char StartUnit, EndUnit;
double StartVal = 0, EndVal = 0;
double CalcVal = 0;
static double result = 0;
//Receive user input
cout << "Please enter the unit which you would like to convert from: ";
cin >> StartUnit;
cout << "What is your initial value?: ";
cin >> StartVal;
cout << "Please enter the unit which you would like to convert to: ";
cin >> EndUnit;
//Step 1: Convert input to celsius
if (StartUnit = 'f')
{
CalcVal = FarCel(StartVal);
}
if (StartUnit = 'k')
{
CalcVal = KelCel(StartVal);
}
if (StartUnit = 'r')
{
CalcVal = RakCel(StartVal);
}
//Step 2: Conver celsius to desired value
cout << CalcVal;
return 0;
}
When I output CalcVal, no matter what, it seems to run through all three functions. It doesn't matter what I type, r, c, f, they all evaluate the same. Could I have some advice on where I'm going wrong?
Solved: Question's answer is that == is used for comparison, my if test used =
Because you seem to assign the values (=), instead of checking them (==). Also you should use else if blocks, for better reading.
All your if-statements assing (=), rather than comparing (==).
So, change this:
if (StartUnit = 'f')
to this:
if (StartUnit == 'f')
and act similar for the rest of the if-statements.
There are three features of C++ that together combine to produce this problem:
In C, C++, and many related language, there is a difference between = (a single equals sign) and == (two equals signs together). The first is an assignment, the second is a comparison. StartUnit = 'f' means "Set StartUnit to the value 'f'"; you meant to use StartUnit == 'f'.
In a lot of languages, and assignment is actually an expression and also has a value. In this case, it's the value assigned, so StartUnit = 'f' means "Set StartUnit to f, and also return the value 'f'". Since it's in an if statement, that both sets StartUnit and does if ('f').
When an if statement or other boolean operation looks at an int, float, char, etc., it checks if they are non-zero. Since 'f' isn't the Nul byte '\x00' (and neither is '0'), it evaluates as true and the if statement body is executed.
Since all of these if statements work the same way, this happens for all of them and all the functions run.
You might also want to use else clauses, or even a switch statement. A bunch of if statements, one after the other, looks like none, any, or all of them could run. Since you want one and only one to happen, you should use else blocks or a switch statement.
bool guess(char c)
{
if (guesses[c])
{
guesses[] = c;
return true;
}
else if (c > ='a' && c <= 'z')
{
guesses[] = c;
return false;
}
}
bool guesses[255] = {};
I need to use this to see if the person has enter a char between a - z and if they haven't I return true else I will return false. either way I will also update guesses with the char. Right now I don't understand how to add char to the array, so that next time I check the it will be false and tell them it was already guessed. I understand this is using the ASCII table but beyond that I am lost. Could anyone explain why this won't work.
I currently get the error
expected primary-expression before']'
but if I take bracket out I get
incompatible type char to bool
which make sense but then how do I make it so where char c is will be mark true in the Boolean array
You've left your brackets empty, so you currently aren't providing an index:
guesses[c] = c;
But you also don't want to assign the char to guesses, you'd want to assign a bool:
guesses[c] = true;
That will compile* and fix your problem.
* Note you also have a syntax error with > =, which I assume was just a copy+paste issue from the editor to the question, but you should fix that also to be >=. Your function guess can also potentially not return (if neither the if or else if are true), which is undefined behaviour. You should ensure all control paths return a value, and you should make sure you compile at the highest warning level so you are warned about these things.
But not your design.
Since you're only dealing with characters a-z, you don't need to allocate all 255 elements like you do. You could simply minus the character to obtain the correct index:
bool guesses[26];
if (c >='a' && c <= 'z')
guesses[c-'a'] = true;
Consider instead using a std::set, a container of unique elements, to track whether a character has been pressed:
#include <set>
std::set<char> guesses;
bool guess(char c)
{
// Have we already inserted this character?
if (guesses.find(c) != std::end(guesses))
{
// Character has already been guessed:
std::cout << "This character has already been guessed";
return true;
}
else if (c >= 'a' && c <= 'z')
{
// Valid guess:
guesses.insert(c);
return false;
}
}
Code, as shown below, can be complied.
Problem: It always says "Invalid Employee id" even when I enter the correct employee id.
Please tell me why and how to do this correctly.
#include <iostream>
#include <iomanip>
using namespace std;
char select, js;
char empid[4];
double bSalary, bonus, tot=0.0;
int main()
{
do
{
cout<<"Employee id: ";
cin>>empid;
if(empid=="M001" || empid=="A004" || empid == "M002") //these are employee ids
{
cout<<"Job Status: ";
cin>>js;
if(js=='P' || js=='C')
{
cout<<"Basic Salary: ";
cin>>bSalary;
if(bSalary>75000 && js=='P')
{
bonus = bSalary*(20.0/100.0);
tot = tot + bonus + bSalary;
}
else if(bSalary>75000 && js=='C')
{
bonus = bSalary*(15.0/100.0);
tot = tot + bonus + bSalary;
}
else
tot = tot+bonus+bSalary;
}
else
cout<<"Invalid Job Status"<<endl;
}
else
cout<<"Invalid Employee no"<<endl;
cout<<"Do you want to continue: ";
cin>>select;
cout<<endl;
}while(select=='y'||select=='Y');
cout<<"Total cost: "<<setprecision(2)<<setiosflags(ios::fixed)<<tot<<endl;
return 0;
}
Note: It is going to the else clause all the time.
It's this:
char empid[4];
This is too small as there's no room for a NUL terminator after the id. You could just change it to 5, but then if someone deliberately or accidentally typed a longer string your program may crash (it's called a buffer overrun, and in some situations can allow whoever provides input to hack the account running the program).
Further, == doesn't work for character arrays: you have to use e.g.:
if (strcmp(empid, "M001") == 0 || strcmp(empid, "A004") == 0 || ...
You would be much better off using a std::string, which will grow to accommodate the actual input (including a NUL terminator though that's not counted in a string's .size()), and works intuitively with ==.
Separately, your...
tot = tot+bonus+bSalary;
...is broken, as bonus may be uninitialised you mustn't read from it in an expression. You can simply remove bonus from the addition above, if it's meant to be 0 for the relevant employees.
You can't compare C strings with == or !=. As you can see that empid here is just a pointer so == will compare the base addresses of those strings not the strings themselves.
You need to use strcmp and include
#include <cstring>
.
.
.
if(strcmp(empid,"M001")==0 || ...)
Empid is not a string. C++ doesn't have a built-in == overload to compare char arrays.
You can make your own == operator. But don't bother. Declare empid as a string and watch magic happen.
string empid;
Changing the size of the char array to take care of NULL char will not work here.
char empid[5]
"==" operator do not work properly with char arrays. please change the condition to below:
if (0 == (strcmp(empid, "M001")) || (0 == (strcmp(empid, "A004"))) || (0 ==
(strcmp(empid, "M002"))))
EDIT:people above has already answered your question. My answer is redundant now.
I need to validate one input string from a user. Eventually it will need to break down into two coordinates. ie a4 c3. And once they are coordinates they need to be broken out into 4 separate ints. a=0 b=1, etc. They must also follow the following stipulations:
If an end-of-input signal is reached the program quits.
Otherwise, all non-alphanumeric characters are discarded from the input.
If what remains is the single letter 'Q'
Then the program quits.
If what remains consists of 4 characters, with one letter and one digit among the first two characters and one letter and one digit among the last two characters, and if each letter-digit pair is in the legal range for our grid
Then input is acceptable.
I have completely over-thought and ruined my function. Please let me know where I can make some corrections.
I am mainly having trouble going from one string, to four chars if and only if the data is valid. Everything else I can handle.
Here is what I have so far.
void Grid::playerMove()
{
string rawMove;
string pair1 = " ";
string pair2 = " ";
bool goodInput = false;
char maxChar = 'a';
char chary1, chary2;
int x11,x22,y11,y22;
for (int i =0; i<size; i++)
{
maxChar++;
}
while(!goodInput)
{
cout<<"What two dots would you like to connect? (Q to quit) ";
cin>>rawMove;
rawMove = reduceWords(rawMove);
if (rawMove == "Q")
{
cout<<"end game";
goodInput = false;
}
else if (rawMove.size() == 4)
{
for(int j=0;j<2;j++)
{
if (pair1[j] >='a' && pair1[j] <=maxChar)
{
chary1 = pair1[j];
}
else if(pair1[j] >=0 && pairl[j]<=size+1)
{
x1 = pair1[j];
}
}
for(int k=0;k<2;k++)
{
if (pair2[k] >='a' && pair2[k] <=maxChar)
{
chary2 = pair2[k];
}
else if(pair2[k] >=0 && pair2[k]<=size+1)
{
x2 = pair2[k];
}
}
}
if(char1 != NULL && char2 != NULL && x1 !=NULL && x2 != NULL)
{
for (int m = 0; m <= size m++)
{
if (char1 == m;)
{
x1 = m;
}
}
for (int n = 0; n <= size n++)
{
if (char2 == n)
{
x2 = n;
}
}
}
}
The end goal would be to have x1, x2, y1, and y2 with their respective values.
Keep in mind I am not allowed to have any external libraries.
It's not clear what exactly you want to achieve, but here are some pointers to get you started:
The while loop will never end because you're setting goodInput to false on quit which lets the loop continue.
The code probably does not even compile? You are missing a curly closing brace..
You are initializing pair1 and pair2 to empty strings but never change them again, so they will never contain any real information about your moves
maybe what you really want is to split up rawMove into the pair1 and pair2 substrings first?
Since this is a homework - and you're supposed to learn from those (right?) - I'm not going to give you the complete answer, but rather something like a recipe:
Use std::istream::getline(char*, std::streamsize s) to read a whole line from std::cin. Make sure you allocate a buffer large enough to hold the expected input (including the terminating null character) plus some more for invalid characters. After the call, check the failbit (input was too long) and the eofbit (hit the end-of-input) of the std::cin stream and handle those cases. Construct a std::string from the buffer if there was no error or EOF has not been reached.
Write a character-classification function (e.g. call it isAlNum(char c)) that returns true if the char argument is alpha-numeric, and false otherwise.
Combine std::string::erase(), std::remove_if(), std::not1(), std::ptr_fun() and your function isAlNum() to sanitise the input string.
Write a function that validates and parses the coordinates from the sanitised input string and call it with the sanitised input string.
Wrap the whole thing in an appropriate while() loop.
This should get you started in the right direction. Of course, if you're allowed to use C++11 features and you know how to write good regular expressions, by all means, use the <regex> header instead of doing the parsing manually.