#029 – Using literal suffixes

Introduction

Consider the following,

#include <iostream>
#include <typeinfo> 

int main() {
    auto y {12.4}; 
    
    std::cout << "The type of y is: " << typeid(y).name();
}

// Output
The type of y is: d

Woah!

Even though we didn’t specify the type of the variable, the compiler was able to deduce it.

When auto is used, the compiler deduces the variable’s type from the initializer. Since literals already have types, this instruction succeeded.

How is this possible?

This is possible since literals have a type. The compiler is smart enough to deduce the type based of the literals in the initializer list.

Use literal suffixes to change the type

We can be explicit about the type e.g. hp = 100u;

This is equivalent to unsigned int hp = 100;

auto very_large_number { 9999LL ); deduces to a long long.

String suffixes

auto name { "Jerry "}; evaluates to a C-style string, however using string suffixes we can change this.

using namespace std::string_view_literals;

auto a { "Mango" };   // string literal
auto b { "Cherry"s };  // std::string
auto c { "Banana"sv }; // std::string_view

Literal suffixes can apply to other types as well.

Data type	Suffix	Meaning
integral	u or U	unsigned int
integral	l or L	long
integral	ul, uL, Ul, UL, lu, lU, Lu, LU	unsigned long
integral	ll or LL	long long
integral	ull, uLL, Ull, ULL, llu, llU, LLu, LLU	unsigned long long
integral	z or Z	The signed version of std::size_t (C++23)
integral	uz, uZ, Uz, UZ, zu, zU, Zu, ZU	std::size_t (C++23)
floating point	f or F	float
floating point	l or L	long double
string	s	std::string
string	sv	std::string_view