POD Types
- char or unsigned char is 1 byte
- float, int, are usually 4 bytes (32 bits) on a 64 bit machine
- double is 8 bytes (64 bits)
- long double is 8, or even 16 bytes
Common Bugs
- Observed Error: error: no matching function for call to ‘min(float, double)’
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// Ensure both arguments are of type float
rk_deltas_[i] = std::min(my_var, 2.0f);
Optional
std::optional can specify if a value is valid or not. It has:
.has_value()to examine if it has value.value()to retrieve the value
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#include <optional>
#include <iostream>
#include <vector>
using namespace std;
void test_optional(){
auto get_ll = [](bool does_return)-> std::optional<size_t> {
if(does_return)
return 1;
else
return {};
};
cout<<get_ll(true).value()<<endl;
if (get_ll(false).has_value()){
cout<<"yay"<<endl;
}
}
int main(){
test_optional();
}
Namespace
::testing::InitGoogleTest(&argc, argv);: defensive way to avoid accidental namespacing issue. This is to call the gtest module
Structural Binding
TODO
iostream
c means “character-based stream” in cin, cout.
-
cout: This is the standard output stream and is buffered by default. This means that data sent to cout is stored in a buffer and is written out (flushed) either when the buffer is full, when a newline is encountered (depending on the implementation and whether the stream is tied to an input stream), or when it is explicitly flushed (usingstd::flushorstd::endl). -
cerr: This stream is meant for error messages and is unbuffered by default, so it flushes its output immediately. This is useful when you want to ensure error messages are output right away. -
clog: Similar to cerr in that it’s used for logging messages, but unlike cerr, clog is buffered. This means it collects log messages in a buffer and flushes them less frequently, which can improve performance.
Because clog is buffered, it can be more efficient for logging non-critical messages since it reduces the number of flush operations. Downside: if your program crashes before the buffer is flushed, some log messages might be lost.
There is clog as well. clog is faster because it stores output to file / screen in a buffer, once the buffer is full, the buffer flushes. In contrast, cout flushes immediately. clog is most useful in writing non-essential logs that could be lost upon system crashes.
