I have made a new string using the existing string. Let say the initial string is
string a="sample"; and the newly created string is
string b=a; Now I have placed the null character at the second index.
b[2]='\0'; when I try to out put the b string.
The output is shown as saple.
I want to end the string after index-1.
Is this behavior normal.If it is normal how to end the string after 1st index.
Thanks..
operator<< is overloaded for std::string. The behavior will differ than if you do this:
char a[] = "sample"; char b[sizeof(a)]; strcpy(b, a); b[2] = '\0'; std::cout << b; or std::cout << b.c_str(); (which calls the overload for a const char* rather than a std::string). The difference between the two overloads is that the overload for const char* calls std::char_traits<char>::length to determine how many characters to print (that is, up to the terminating null character). On the other hand, the overload for std::string uses str.size(). The size of a std::string includes any null characters embedded in it.1
In order to "truncate" a string, you can follow @Wimmel's suggestion and use resize:
std::string a = "sample"; std::string b = a; b.resize(2); std::cout << b; I'm not sure what the standard defines should happen with what you are currently doing, but the proper way to do what you are trying to achieve is using std::string::substr() method like this:
b = a.substr(0, index-1); It is normal.
unlike C string, the lenght of std::string is not determined by '\0', instead, there's a member variable recording its length. in the case, the string content is 73 61 00 70 6c 65, thus, b.length() == 6, though there's a '\0' in it. you also can redirect the output into a file, and check the content, it is 73 61 00 70 6c 65.
If you wanna to truncate the string, call b.resize(2).
std::stringand "C-style" string concepts.