How to get the number of characters in a std::stri

Question

How should I get the number of characters in a string in C++?

Answer 1

if you're using std::string, there are two common methods for that:

std::string Str("Some String");
size_t Size = 0;
Size = Str.size();
Size = Str.length();

if you're using the C style string (using char * or const char *) then you can use:

const char *pStr = "Some String";
size_t Size = strlen(pStr);

Answer 2

In C++ std::string the length() and size() method gives you the number of bytes, and not necessarily the number of characters !. Same with the c-Style sizeof() function!

For most of the printable 7bit-ASCII Characters this is the same value, but for characters that are not 7bit-ASCII it's definitely not. See the following example to give you real results (64bit linux).

There is no simple c/c++ function that can really count the number of characters. By the way, all of this stuff is implementation dependent and may be different on other environments (compiler, win 16/32, linux, embedded, ...)

See following example:

#include <string>
#include <iostream>
#include <stdio.h>
#include <string.h>
using namespace std;

int main()
{
/* c-Style char Array */
const char * Test1 = "1234";
const char * Test2 = "ÄÖÜ€";
const char * Test3 = "αβγ                                                                    

                                                        
            

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Answer 3

It depends on what string type you're talking about. There are many types of strings:

1. const char* - a C-style multibyte string
2. const wchar_t* - a C-style wide string
3. std::string - a "standard" multibyte string
4. std::wstring - a "standard" wide string

For 3 and 4, you can use .size() or .length() methods.

For 1, you can use strlen(), but you must ensure that the string variable is not NULL (=== 0)

For 2, you can use wcslen(), but you must ensure that the string variable is not NULL (=== 0)

There are other string types in non-standard C++ libraries, such as MFC's CString, ATL's CComBSTR, ACE's ACE_CString, and so on, with methods such as .GetLength(), and so on. I can't remember the specifics of them all right off the top of my head.

The STLSoft libraries have abstracted this all out with what they call string access shims, which can be used to get the string length (and other aspects) from any type. So for all of the above (including the non-standard library ones) using the same function stlsoft::c_str_len(). This article describes how it all works, as it's not all entirely obvious or easy.

Answer 4

It might be the easiest way to input a string and find its length.

// Finding length of a string in C++ 
#include<iostream>
#include<string>
using namespace std;

int count(string);

int main()
{
string str;
cout << "Enter a string: ";
getline(cin,str);
cout << "\nString: " << str << endl;
cout << count(str) << endl;

return 0;

}

int count(string s){
if(s == "")
  return 0;
if(s.length() == 1)
  return 1;
else
    return (s.length());

}

Answer 5

Simplest way to get length of string without bothering about std namespace is as follows

string with/without spaces

#include <iostream>
#include <string>
using namespace std;
int main(){
    string str;
    getline(cin,str);
    cout<<"Length of given string is"<<str.length();
    return 0;
}

string without spaces

#include <iostream>
#include <string>
using namespace std;
int main(){
    string str;
    cin>>str;
    cout<<"Length of given string is"<<str.length();
    return 0;
}