Quick Q: Why is list initialization (using curly braces) better than the alternatives?
Quick A: It is less likely to generate an unexpected error.
Recently on SO:
Why is list initialization (using curly braces) better than the alternatives?
Basically copying and pasting from Bjarne Stroustrup's "The C++ Programming Language 4th Edition":
List initialization does not allow narrowing (§iso.8.5.4). That is:
- An integer cannot be converted to another integer that cannot hold its value. For example, char to int is allowed, but not int to char.
- A floating-point value cannot be converted to another floating-point type that cannot hold its value. For example, float to double is allowed, but not double to float.
- A floating-point value cannot be converted to an integer type.
- An integer value cannot be converted to a floating-point type.
Example:
void fun(double val, int val2) { int x2 = val; // if val==7.9, x2 becomes 7 (bad) char c2 = val2; // if val2==1025, c2 becomes 1 (bad) int x3 {val}; // error: possible truncation (good) char c3 {val2}; // error: possible narrowing (good) char c4 {24}; // OK: 24 can be represented exactly as a char (good) char c5 {264}; // error (assuming 8-bit chars): 264 cannot be // represented as a char (good) int x4 {2.0}; // error: no double to int value conversion (good) }The only situation where = is preferred over {} is when using auto keyword to get the type determined by the initializer.
Example:
auto z1 {99}; // z1 is an initializer_list<int> auto z2 = 99; // z2 is an intConclusion
Prefer {} initialization over alternatives unless you have a strong reason not to.