Programming Forums > Application Development > C++

titaniumdecoy · Feb 16th, 2006, 10:42 PM

How do you initialize a string as a character in C++?

In Java you would use:

char c = 'c';
String str = Character.toString(c);

Also, how do you convert a character to a string in general?

Jimbo · Feb 16th, 2006, 11:35 PM

There is a string constructor that takes a C-string and one that takes a char array and a length (c-string being a null-terminated char array or string literal). If you know what the letter you want is, you can just use:

(Toggle Plain Text)

string str("c");

or if you want it to depend on a variable, whether user input or whatever, you can just use:

(Toggle Plain Text)

char c = /* whatever */;
string str(&c, 1);

titaniumdecoy · Feb 16th, 2006, 11:39 PM

Thanks for your help.

Also, how do you append characters (chars) to a string?

Jimbo · Feb 16th, 2006, 11:54 PM

string has an operator+= defined, which as I remember takes another string or the same char* arguments listed above

titaniumdecoy · Feb 16th, 2006, 11:56 PM

Why doesn't this code give me the first 2 characters of str1 as a string?

(Toggle Plain Text)

string str1("27582347502458270");
string s(str1[0], 1);
s.append(&str1[1]);
cout << s << endl;

Jimbo · Feb 17th, 2006, 12:04 AM

first off, remember that the constructor takes a char* not a char (as operator[] returns), so the 2nd line should probably be

(Toggle Plain Text)

string s(str1.c_str(),1); // get the char*
// or an alternative
string s(&str[0], 1); // get a pointer to the first char

for the append, unless you specifiy a length, it will append data until it reaches a null character (with integer value 0). Since the string is (I believe) stored as a char* in memory, it keeps reading until it reaches the end, hence you have more than 2 characters. That's easily solved with

(Toggle Plain Text)

s.append(&str[1], 1);

titaniumdecoy · Feb 17th, 2006, 12:40 AM

Thanks again, Jimbo.

Is there a website that has the official documentation for C++? For Java there is http://java.sun.com/j2se/1.3/docs/api/java/lang/. Thanks.

Jimbo · Feb 17th, 2006, 12:49 AM

I usually just use MSDN, especially since I use Visual Studio. I believe Microsoft's implementation is starting to follow the standard well enough to use it as a general reference anyways. Otherwise, just google around. I think there's another website like cplusplus.com or something like that, which has some decent documentation on a few standard header functions. I don't think there's a standard site, however.

By the way, your link for Java is a bit old... http://java.sun.com/j2se/1.5.0/docs/api/ is a little more like it...

Polyphemus_ · Feb 17th, 2006, 1:08 PM

IIRC, you can just do this, since the stl string overloads the = operator:

(Toggle Plain Text)

char *str = "Some C-style string";

string cppStr = str;

Feb 16th, 2006, 10:42 PM	#1
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 843 Rep Power: 3	char to string in C++ How do you initialize a string as a character in C++? In Java you would use: char c = 'c'; String str = Character.toString(c); Also, how do you convert a character to a string in general?

Feb 16th, 2006, 11:35 PM	#2
Jimbo Battle Programmer Join Date: Feb 2006 Location: Bellevue, WA, USA Posts: 754 Rep Power: 3	There is a string constructor that takes a C-string and one that takes a char array and a length (c-string being a null-terminated char array or string literal). If you know what the letter you want is, you can just use: (Toggle Plain Text) string str("c"); string str("c"); or if you want it to depend on a variable, whether user input or whatever, you can just use: (Toggle Plain Text) char c = /* whatever /; string str(&c, 1); char c = / whatever */; string str(&c, 1);

Feb 16th, 2006, 11:56 PM	#5
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 843 Rep Power: 3	Why doesn't this code give me the first 2 characters of str1 as a string? (Toggle Plain Text) string str1("27582347502458270"); string s(str1[0], 1); s.append(&str1[1]); cout << s << endl; string str1("27582347502458270"); string s(str1[0], 1); s.append(&str1[1]); cout << s << endl;

Feb 17th, 2006, 12:04 AM	#6
Jimbo Battle Programmer Join Date: Feb 2006 Location: Bellevue, WA, USA Posts: 754 Rep Power: 3	first off, remember that the constructor takes a char* not a char (as operator[] returns), so the 2nd line should probably be (Toggle Plain Text) string s(str1.c_str(),1); // get the char* // or an alternative string s(&str[0], 1); // get a pointer to the first char string s(str1.c_str(),1); // get the char* // or an alternative string s(&str[0], 1); // get a pointer to the first char for the append, unless you specifiy a length, it will append data until it reaches a null character (with integer value 0). Since the string is (I believe) stored as a char* in memory, it keeps reading until it reaches the end, hence you have more than 2 characters. That's easily solved with (Toggle Plain Text) s.append(&str[1], 1); s.append(&str[1], 1);

Feb 17th, 2006, 1:08 PM	#9
Polyphemus_ Expert Programmer Join Date: Aug 2005 Location: Rotterdam, the Netherlands Posts: 942 Rep Power: 4	IIRC, you can just do this, since the stl string overloads the = operator: (Toggle Plain Text) char str = "Some C-style string"; string cppStr = str; char str = "Some C-style string"; string cppStr = str;

Feb 16th, 2006, 11:39 PM	#3
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 843 Rep Power: 3	Thanks for your help. Also, how do you append characters (chars) to a string?

Feb 16th, 2006, 11:54 PM	#4
Jimbo Battle Programmer Join Date: Feb 2006 Location: Bellevue, WA, USA Posts: 754 Rep Power: 3	string has an operator+= defined, which as I remember takes another string or the same char* arguments listed above

Feb 17th, 2006, 12:40 AM	#7
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 843 Rep Power: 3	Thanks again, Jimbo. Is there a website that has the official documentation for C++? For Java there is http://java.sun.com/j2se/1.3/docs/api/java/lang/. Thanks.

Feb 17th, 2006, 12:49 AM	#8
Jimbo Battle Programmer Join Date: Feb 2006 Location: Bellevue, WA, USA Posts: 754 Rep Power: 3	I usually just use MSDN, especially since I use Visual Studio. I believe Microsoft's implementation is starting to follow the standard well enough to use it as a general reference anyways. Otherwise, just google around. I think there's another website like cplusplus.com or something like that, which has some decent documentation on a few standard header functions. I don't think there's a standard site, however. By the way, your link for Java is a bit old... http://java.sun.com/j2se/1.5.0/docs/api/ is a little more like it...

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Programming Forums > Application Development > C++

char to string in C++