有关字符和字符串的C ++

Question

what is char ctemp = ' '; and string stemp = ""; means? when they put ' ' and " " inside without writing anything inside? Help please! Will appreciate who answer it.

Answer 1

Single quotes ( ' ) indicate a character literal: a single character. Double quotes ( " ) denote a string literal, ie: an array of characters.

' ' is a single space character, while " " is a single space character followed by a null terminator, as is customary for C-style strings.

Character literals are directly assignable to char variables.

The type of a string literal is const char[N] , where N is the length of the literal, including the null terminator. In C and C++, a static array decays to (is implicitly convertible to) a pointer to the first element, and std::string is constructible from a const char * pointer (see constructor (5)), which in C usually means a pointer to an array of characters terminated by a null terminator.

Answer 2

The char ctemp = ' ' will put the value ' ' (32 in ASCII decimal) inside the ctemp variable.
The string stemp = ""; will create an empty string in stemp .

Answer 3

Here

char ctemp = ' ';

you are assigning a whitespace character ' ' to ctemp .

Here

string stemp = "";

the initializer "" creates a empty string.

Answer 4

' ' is the space character. "" is an empty string. " " is a string that contains only the space character. Note that a statement like string stemp = "" implicitly invokes the string(char const *) constructor to create a new string instance from a char const * pointer.

Answer 5

the first one means a "whitespace" like when you write something and need to divide the words with the space key. That empty space is still part of the string and so you can say your char is only that empty space.

The second one is of type string but it is even less than a white space. It is a completely empty string.

Answer 6

string is array(collection) of char

ctemp = ' ' 

mean whitespace character

stemp = ""

mean empty string no character in string

you can put ' ' to char variable. you can put " " to array of char.

Answer 7

The answers above only state about the space literal, but I think OP wants to ask why people write something like
string temp ="" ;

The answer is that it initializes a string object. If you would write
string temp;
You would get undefined behaviour if you would try to access it since it isn't initialized. Initializing an empty string let's you concatenate it with something easily. Concatenating an empty string with another string is basically a replace.

It's a bit different for char since it is a primitive type and not an object. Writing
char tmp; already initializes it to the default value of \\0 . chars can be used right away.

Answer 8

In C++ the single quote is used to identify the single character, and double quotes are used for string literals. A string literal “x” is a string, it is containing character 'x' and a null terminator '\\0'. So “x” is two-character array in this case.

Some Examples:
string s = "" ; => empty string
char s =' ' ;   => space (you should have only one character inside the single quotes)
string s = " " ; => space followed by '\0' character (two character array)

Answer 9

Whitespace character and empty string. You can see the string as a sequence of characters, but they are two different types