CODEWITHSUNDEEP
c++
askoasksao
askoasksao

Reputation: 97

C++ gives random value when combining chars

I have a string 039 and i have this following code

cout<<str2[1]+str2[0]+str2[2]<<endl;

I expect this to give me 309,but it gives me 156.How is that considering that separately all they give me 3 0 9?

Upvotes: 0

Views: 88

Answers (3)

Ron
Ron

Reputation: 15521

It is because you are summing the characters / their underlying integral values together. If you want to output the characters themselves use the << operator, not the +. The characters and their underlying values are (assuming ASCII): 

'3'    51  
'0'    48  
'9'    57

The expression of:

str2[1] + str2[0] + str2[2]

sums the characters together, it does not send them to standard output one by one, so the expression becomes:

51 + 48 + 57

resulting in 156. Use the operator<< instead:

#include <iostream>
#include <string>

int main() {
    std::string str2 = "039";
    std::cout << str2[1] << str2[0] << str2[2] << '\n';
}

As pointed out in the comments, character types are integral types and your char type probably covers the range from -127 to 127. This also assumes you are using ASCII encoding which maps the characters to values given above.

Upvotes: 6

yannick ott
yannick ott

Reputation: 76

If you need retrieve result as a string use ostringstream :

#include <sstream>
std::ostringstream stream;
stream << str2[1] << str2[0]<< str2[2];
std::string res = stream.str();
std::cout <<"> " << res << std::endl;

Upvotes: 0

J K
J K

Reputation: 642

If str2[1] is char, then:

Char is just like int, but from -127 to 127(or 0 to 255). See ASCII codes.
Then if you do str2[1]+str2[0]+str2[2], you will get some ASCII code.
In c++ you can't do char+char and get 2 chars. Do this:

cout<<str2[1]<<str2[0]<<str2[2]<<endl;

Upvotes: 1

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