1、直接使用字符串相加
std::string a = "hello";
std::string b = "hello";
for(int i = 0; i < 100; ++i)
{
a = b + a;
}
2、使用insert函数
std::string a = "hello";
for(int i = 0; i < 100; ++i)
{
a.insert(0, "hello");
}
比较:通过Quick C++ Benchmarks 可得到结果
static void StringCreation(benchmark::State& state) {
// Code inside this loop is measured repeatedly
std::string x = "hello";
for (auto _ : state) {
x.insert(0,"hello");
// Make sure the variable is not optimized away by compiler
benchmark::DoNotOptimize(x);
}
}
// Register the function as a benchmark
BENCHMARK(StringCreation);
static void StringCopy(benchmark::State& state) {
// Code before the loop is not measured
std::string x = "hello";
for (auto _ : state) {
x = "hello" + x;
}
}
BENCHMARK(StringCopy);