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Modifying a QString that contains a “”

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1

I'm trying to modify a QString. The Qstring that I'm trying to modify is

"02"

However when I try to modify it, the string either gets entirely deleted or shows no change.

I've tried

String.split(""");
String.remove(""");
String.remove(QChar(''');

for some reason Qt requires that I add an extra " or ' in order to compile and not produce errors

What I currently have is this

string = pointer->data.info.get_type();

which according to the debugger returns "02"

string = string.remove(QChar('''));

the remove functionality does nothing afterwards.

I'm expecting to remove the from the string, but either it gets entirely deleted or nothing happens. What could be the problem and how do I modify the Qstring to just be the numerical values?

c++ qt qstring

share|improve this question

asked Mar 26 at 15:55

BChiuBChiu

2977 bronze badges

• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  You should read up about escape sequences in c++ strings. You need "\" not """ to search for a slash, the second one searches for a quote
  
  – Alan Birtles
  Mar 26 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You want String.split("\"); , not String.split("""); .
  
  – Jesper Juhl
  Mar 26 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Put another way: What would you think is the reason that there are three instances of " in String.split(""");? It appears that the compiler complained about an unclosed string/character literal and you just added a " to shut it up without considering why "" didn't work.
  
  – Max Langhof
  Mar 26 at 16:14
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  question is about C++ basic, but it is well written question, describing what is expected and what is seen, so I will vote it up.
  
  – Marek R
  Mar 26 at 16:20
  
  

  
  
  
  

add a comment | 

1

I'm trying to modify a QString. The Qstring that I'm trying to modify is

"02"

However when I try to modify it, the string either gets entirely deleted or shows no change.

I've tried

String.split(""");
String.remove(""");
String.remove(QChar(''');

for some reason Qt requires that I add an extra " or ' in order to compile and not produce errors

What I currently have is this

string = pointer->data.info.get_type();

which according to the debugger returns "02"

string = string.remove(QChar('''));

the remove functionality does nothing afterwards.

I'm expecting to remove the from the string, but either it gets entirely deleted or nothing happens. What could be the problem and how do I modify the Qstring to just be the numerical values?

c++ qt qstring

share|improve this question

asked Mar 26 at 15:55

BChiuBChiu

2977 bronze badges

• 
  
  
  

  
  4
  

  
  
  
  
  
  

  
  
  You should read up about escape sequences in c++ strings. You need "\" not """ to search for a slash, the second one searches for a quote
  
  – Alan Birtles
  Mar 26 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You want String.split("\"); , not String.split("""); .
  
  – Jesper Juhl
  Mar 26 at 15:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Put another way: What would you think is the reason that there are three instances of " in String.split(""");? It appears that the compiler complained about an unclosed string/character literal and you just added a " to shut it up without considering why "" didn't work.
  
  – Max Langhof
  Mar 26 at 16:14
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  question is about C++ basic, but it is well written question, describing what is expected and what is seen, so I will vote it up.
  
  – Marek R
  Mar 26 at 16:20
  
  

  
  
  
  

add a comment | 

I'm trying to modify a QString. The Qstring that I'm trying to modify is

"02"

However when I try to modify it, the string either gets entirely deleted or shows no change.

I've tried

String.split(""");
String.remove(""");
String.remove(QChar(''');

for some reason Qt requires that I add an extra " or ' in order to compile and not produce errors

What I currently have is this

string = pointer->data.info.get_type();

which according to the debugger returns "02"

string = string.remove(QChar('''));

the remove functionality does nothing afterwards.

I'm expecting to remove the from the string, but either it gets entirely deleted or nothing happens. What could be the problem and how do I modify the Qstring to just be the numerical values?

c++ qt qstring

share|improve this question

asked Mar 26 at 15:55

BChiuBChiu

2977 bronze badges

"02"

String.split(""");
String.remove(""");
String.remove(QChar(''');

string = pointer->data.info.get_type();

string = string.remove(QChar('''));

share|improve this question

asked Mar 26 at 15:55

BChiuBChiu

2977 bronze badges

share|improve this question

asked Mar 26 at 15:55

BChiuBChiu

2977 bronze badges

asked Mar 26 at 15:55

BChiuBChiu

2977 bronze badges

asked Mar 26 at 15:55

BChiuBChiu

2977 bronze badges

2 Answers
2

active

oldest

votes

6

You're currently asking Qt to remove " from your string, not . To remove , you'll have to escape it, just like you escaped ", i.e. remove("\").

share|improve this answer

answered Mar 26 at 15:58

gsprgspr

7,68422 gold badges3030 silver badges6363 bronze badges

add a comment | 

3

First of all your string "02" do not contain any slash, quotes or apostrophes.
Read about C++ string literals. This is escape sequence.
Note nnn represents arbitrary octal value!

So your literal contains only one character of value decimal value 2! This is ASCII spatial code meaning: STX (start of text)

As a result this code:

String.split(""");
String.remove(""");
String.remove(QChar(''');

won't split or anything since this string do not contain quote characters or apostrophe. It also do not tries split or remove slash character, since again this is an escape sequence, but different kind.

Now remember that debugger shows you this unprintable characters in escaped form to show you actual content. In live application user will see nothing or some strange glyph.

share|improve this answer

edited Mar 26 at 16:15

answered Mar 26 at 16:10

Marek RMarek R

14.9k33 gold badges3030 silver badges8181 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  It really depends, maybe "02" is truly what the string contains (i.e. the source code actually has "\002", although I wouldn't bet on that). You got my +1 though because this aspect is indeed important to be aware of here.
  
  – Max Langhof
  Mar 26 at 16:20
  
  

  
  
  
  

add a comment | 

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6

You're currently asking Qt to remove " from your string, not . To remove , you'll have to escape it, just like you escaped ", i.e. remove("\").

share|improve this answer

answered Mar 26 at 15:58

gsprgspr

7,68422 gold badges3030 silver badges6363 bronze badges

add a comment | 

6

You're currently asking Qt to remove " from your string, not . To remove , you'll have to escape it, just like you escaped ", i.e. remove("\").

share|improve this answer

answered Mar 26 at 15:58

gsprgspr

7,68422 gold badges3030 silver badges6363 bronze badges

add a comment | 

You're currently asking Qt to remove " from your string, not . To remove , you'll have to escape it, just like you escaped ", i.e. remove("\").

share|improve this answer

answered Mar 26 at 15:58

gsprgspr

7,68422 gold badges3030 silver badges6363 bronze badges

share|improve this answer

answered Mar 26 at 15:58

gsprgspr

7,68422 gold badges3030 silver badges6363 bronze badges

answered Mar 26 at 15:58

gsprgspr

7,68422 gold badges3030 silver badges6363 bronze badges

answered Mar 26 at 15:58

gsprgspr

7,68422 gold badges3030 silver badges6363 bronze badges

3

First of all your string "02" do not contain any slash, quotes or apostrophes.
Read about C++ string literals. This is escape sequence.
Note nnn represents arbitrary octal value!

So your literal contains only one character of value decimal value 2! This is ASCII spatial code meaning: STX (start of text)

As a result this code:

String.split(""");
String.remove(""");
String.remove(QChar(''');

won't split or anything since this string do not contain quote characters or apostrophe. It also do not tries split or remove slash character, since again this is an escape sequence, but different kind.

Now remember that debugger shows you this unprintable characters in escaped form to show you actual content. In live application user will see nothing or some strange glyph.

share|improve this answer

edited Mar 26 at 16:15

answered Mar 26 at 16:10

Marek RMarek R

14.9k33 gold badges3030 silver badges8181 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  It really depends, maybe "02" is truly what the string contains (i.e. the source code actually has "\002", although I wouldn't bet on that). You got my +1 though because this aspect is indeed important to be aware of here.
  
  – Max Langhof
  Mar 26 at 16:20
  
  

  
  
  
  

add a comment | 

3

First of all your string "02" do not contain any slash, quotes or apostrophes.
Read about C++ string literals. This is escape sequence.
Note nnn represents arbitrary octal value!

So your literal contains only one character of value decimal value 2! This is ASCII spatial code meaning: STX (start of text)

As a result this code:

String.split(""");
String.remove(""");
String.remove(QChar(''');

won't split or anything since this string do not contain quote characters or apostrophe. It also do not tries split or remove slash character, since again this is an escape sequence, but different kind.

Now remember that debugger shows you this unprintable characters in escaped form to show you actual content. In live application user will see nothing or some strange glyph.

share|improve this answer

edited Mar 26 at 16:15

answered Mar 26 at 16:10

Marek RMarek R

14.9k33 gold badges3030 silver badges8181 bronze badges

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  It really depends, maybe "02" is truly what the string contains (i.e. the source code actually has "\002", although I wouldn't bet on that). You got my +1 though because this aspect is indeed important to be aware of here.
  
  – Max Langhof
  Mar 26 at 16:20
  
  

  
  
  
  

add a comment | 

First of all your string "02" do not contain any slash, quotes or apostrophes.
Read about C++ string literals. This is escape sequence.
Note nnn represents arbitrary octal value!

So your literal contains only one character of value decimal value 2! This is ASCII spatial code meaning: STX (start of text)

As a result this code:

String.split(""");
String.remove(""");
String.remove(QChar(''');

won't split or anything since this string do not contain quote characters or apostrophe. It also do not tries split or remove slash character, since again this is an escape sequence, but different kind.

Now remember that debugger shows you this unprintable characters in escaped form to show you actual content. In live application user will see nothing or some strange glyph.

share|improve this answer

edited Mar 26 at 16:15

answered Mar 26 at 16:10

Marek RMarek R

14.9k33 gold badges3030 silver badges8181 bronze badges

String.split(""");
String.remove(""");
String.remove(QChar(''');

share|improve this answer

edited Mar 26 at 16:15

answered Mar 26 at 16:10

Marek RMarek R

14.9k33 gold badges3030 silver badges8181 bronze badges

answered Mar 26 at 16:10

Marek RMarek R

14.9k33 gold badges3030 silver badges8181 bronze badges

answered Mar 26 at 16:10

Marek RMarek R

14.9k33 gold badges3030 silver badges8181 bronze badges