CODEWITHSUNDEEP
c++stringchar
james
james

Reputation: 567

What is the difference between 'a' (with single quotes) and "a" (with double quotes)?

I am learning C++ and have got a question that I cannot find the answer to.

What is the difference between a char constant (using single quotes) and a string constant (with double quotes)?

All my search results related to char arrays vs std::string. I am after the difference between 'a' and "a".

Would there be a difference in doing the following:

cout << "a";
cout << 'a';

Upvotes: 16

Views: 47694

Answers (6)

ganga
ganga

Reputation: 1

'a' - 1) Character constant 2) size - 1 Character 3) Not a collection of Character array

"a" -1) String literals 2) size - 2 Character 3) collection of Character array

Upvotes: -1

user3425449
user3425449

Reputation: 11

  • "a" -> it denotes it is a string. in c++ string is a collection of characters array.
  • so string is terminated by delimiter '\0' it indicates the end of string.
  • so its size would be 2 because 1-byte for "a" and 1-byte for '\0'

where in case of 'a'-> it is single character. so its size would be 1-byte.

char str[]="a";

or 

char *ptr = "c";

for  'c' -> char c = 'a';

or we can write as well 

char c = 97;

Upvotes: 0

Keith Thompson
Keith Thompson

Reputation: 263177

'a' is a character literal. It's of type char, with the value 97 on most systems (the ASCII/Latin-1/Unicode encoding for the letter a).

"a" is a string literal. It's of type const char[2], and refers to an array of 2 chars with values 'a' and '\0'. In most, but not all, contexts, a reference to "a" will be implicitly converted to a pointer to the first character of the string.

Both

cout << 'a';

and

cout << "a";

happen to produce the same output, but for different reasons. The first prints a single character value. The second successively prints all the characters of the string (except for the terminating '\0') -- which happens to be the single character 'a'.

String literals can be arbitrarily long, such as "abcdefg". Character literals almost always contain just a single character. (You can have multicharacter literals, such as 'ab', but their values are implementation-defined and they're very rarely useful.)

(In C, which you didn't ask about, 'a' is of type int, and "a" is of type char[2] (no const)).

Upvotes: 37

ThomasMcLeod
ThomasMcLeod

Reputation: 7769

A single quoted 'a' is a literal of type char. A double quoted "a" is a null-terminated string literal of chars.

Upvotes: 0

Hot Licks
Hot Licks

Reputation: 47699

Single quotes are used to surround character literals. Double quotes are used to surround string (character array) literals.

Many interfaces, such as cout <<, accept either.

Upvotes: 1

Ry-
Ry-

Reputation: 224862

"a" is an array of characters that just happens to only contain one character, or two if you count the \0 at the end. 'a' is one character. They're not the same thing. For example:

#include <stdio.h>

void test(char c) {
    printf("Got character %c\n", c);
}

void test(const char* c) {
    printf("Got string %s\n", c);
}

int main() {
    test('c');
    test("c");
}

This will use two different overloads; see http://codepad.org/okl0UcCN for a demo.

Upvotes: 4

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