AntoniRyszard656
asked on
Testing strings?
Hello,
I was trying to test if the far right character in a string equalled #.
And thought it would be a good idea to trim the right of string to move any spaces.
I found this code on the web:
string rtrim(const string &str){
int idx = str.find_last_not_of("\t ");
if(idx != string::npos)
return str.substr(0,idx+1);
return str;
}
But, when I tested the string using:
if(string.length()-1 == '#'){
//some action
}
All tested strings seemed to be regarded as if the last character equalled #, even when the # was at the start of the string rather than on the right.
Any thoughts?
I was trying to test if the far right character in a string equalled #.
And thought it would be a good idea to trim the right of string to move any spaces.
I found this code on the web:
string rtrim(const string &str){
int idx = str.find_last_not_of("\t ");
if(idx != string::npos)
return str.substr(0,idx+1);
return str;
}
But, when I tested the string using:
if(string.length()-1 == '#'){
//some action
}
All tested strings seemed to be regarded as if the last character equalled #, even when the # was at the start of the string rather than on the right.
Any thoughts?
Your comparison was
str.length () -1 == (int) ('#') = 35
so the if part would only be executed ifthe length of the string was 36 (-1 = 35)
str.length () -1 == (int) ('#') = 35
so the if part would only be executed ifthe length of the string was 36 (-1 = 35)
ASKER
Thanks
Would you recommend using this method to remove the empty spaces from the right of a string or is there some better approach?
string rtrim(const string &str){
int idx = str.find_last_not_of("\t ");
if(idx != string::npos)
return str.substr(0,idx+1);
return str;
}
Would you recommend using this method to remove the empty spaces from the right of a string or is there some better approach?
string rtrim(const string &str){
int idx = str.find_last_not_of("\t ");
if(idx != string::npos)
return str.substr(0,idx+1);
return str;
}
ASKER
Hello,
I tried using the indexing operator, in this example. But found when I entered:
# test
The if statement was entered, and "Working" displayed. I was hoping only when the string ended with # would the program enter the if statement.
Could anyone see the problem?
Thanks
#include <iostream>
#include <conio.h>
using namespace std;
int main(int argc, char *argv[]){
string input;
while(input!="exit"){
cout << "Enter text: ";
cin >> input;
if(input[input.length()-1]
cout << endl<< "Working";
getch();
}
system("cls");
}
return 0;
}
I tried using the indexing operator, in this example. But found when I entered:
# test
The if statement was entered, and "Working" displayed. I was hoping only when the string ended with # would the program enter the if statement.
Could anyone see the problem?
Thanks
#include <iostream>
#include <conio.h>
using namespace std;
int main(int argc, char *argv[]){
string input;
while(input!="exit"){
cout << "Enter text: ";
cin >> input;
if(input[input.length()-1]
cout << endl<< "Working";
getch();
}
system("cls");
}
return 0;
}
ASKER
Could I use getchar()?
When you read into a string from a stream, you get a word, not a line. In your test case, because there was a space after the '#', the string was set to the first word only: "#". So the program correctly reported that the last character of the string was '#'.
You could try the getline function to read a whole line into the string.
getline(cin, input);
This should work, but when I tried it, I had to hit Enter twice to get the program to accept my input.
--efn
You could try the getline function to read a whole line into the string.
getline(cin, input);
This should work, but when I tried it, I had to hit Enter twice to get the program to accept my input.
--efn
ASKER
Thanks
Do you think changing the string input to a char * could make the end character easier to test?
Do you think changing the string input to a char * could make the end character easier to test?
ASKER CERTIFIED SOLUTION
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ASKER
Thanks,
Could you also demonstrate the alternative use of getline.
And is there any way to stop the need to press Enter twice, that (efn) mentioned?
Could you also demonstrate the alternative use of getline.
And is there any way to stop the need to press Enter twice, that (efn) mentioned?
> And is there any way to stop the need to press Enter twice, that (efn) mentioned?
Yes, this is a known bug in the Microsoft Visual C++ 6.0 library. If you don't have that compiler, you may not have the bug. The fix is here:
http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/Q240/0/15.ASP&NoWebContent=1
Courtesy of DanRollins in this PAQ:
https://www.experts-exchange.com/questions/20180499/getline.html
--efn
Yes, this is a known bug in the Microsoft Visual C++ 6.0 library. If you don't have that compiler, you may not have the bug. The fix is here:
http://support.microsoft.com/default.aspx?scid=http://support.microsoft.com:80/support/kb/articles/Q240/0/15.ASP&NoWebContent=1
Courtesy of DanRollins in this PAQ:
https://www.experts-exchange.com/questions/20180499/getline.html
--efn
ASKER
Thanks I will try this, I am using Dev-C++ which I believe uses the latest compile.
if(str[str.length()-1] == '#'){
//some action
}