【C++ 小问答】2：平台对隐式类型转换的影响

1unsigned int a = ...;
2long b = ...;
3auto c = a + b;  // 此处 auto 会推导出什么类型？

 1#include <iostream>
 2#include <typeinfo>
 3
 4int main()
 5{
 6    unsigned int var_a = 4;
 7    long var_b = 5;
 8    auto var_c = var_a + var_b;
 9    ::std::cout << "var_a: " << typeid(var_a).name() << ::std::endl;
10    ::std::cout << "var_a: " << sizeof(var_a) << ::std::endl;
11    ::std::cout << "var_b: " << typeid(var_b).name() << ::std::endl;
12    ::std::cout << "var_b: " << sizeof(var_b) << ::std::endl;
13    ::std::cout << "var_c: " << typeid(var_c).name() << ::std::endl;
14    ::std::cout << "var_c: " << sizeof(var_c) << ::std::endl;
15}

1g++ main.cpp && ./a.out | c++filt -t

1var_a: unsigned int
2var_a: 4
3var_b: long
4var_b: 8
5var_c: long
6var_c: 8

1g++ -m32 main.cpp && ./a.out | c++filt -t

1var_a: unsigned int
2var_a: 4
3var_b: long
4var_b: 4
5var_c: unsigned long
6var_c: 4