auto changes meaning in C++11; please remove it what does this mean?
The new meaning of auto
(deduce the type) was introduced in C++11. Compile your code with the flag -std=c++11
.
john
Updated on June 24, 2022Comments
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john almost 2 years
I am running my below code which checks whether
data_timestamp
is more than two weeks old or not. If it is two weeks old, then print hello otherwise prints world.I am a Java developer, recently started working with C++. Learned few things over internet so I am using it here in this program.
#include <ctime> #include <chrono> #include <iostream> int main() { // this has to be uint64_t bcoz of old code uint64_t data_timestamp = 1406066507000; const auto now = std::chrono::system_clock::now(); auto twoWeeks = std::chrono::hours(24 * 14); auto lastTwoWeeks = now - twoWeeks; auto millis = std::chrono::duration_cast<std::chrono::milliseconds>(lastTwoWeeks.time_since_epoch()).count(); std::cout << "Time stamp in milliseconds since UNIX epoch start: "<< millis << std::endl; if (data_timestamp < millis) { std::cout << "Hello"; } else { std::cout << "World"; } return 0; }
I will be running this code on Ubuntu 12.04. When I am compiling it while running
make install
, it is giving me this exception -warning: âautoâ changes meaning in C++11; please remove it [-Wc++0x-compat] error: ânowâ does not name a type warning: âautoâ changes meaning in C++11; please remove it [-Wc++0x-compat] âtwoWeeksâ does not name a type warning: âautoâ changes meaning in C++11; please remove it [-Wc++0x-compat] error: âlastTwoWeeksâ does not name a type warning: âautoâ changes meaning in C++11; please remove it [-Wc++0x-compat] error: âmillisâ does not name a type error: âmillisâ was not declared in this scope
May be, I am not having
C++11
. This is a simple program which I made but the core logic of this program I am using it in a big C++ project so it looks like, I cannot port everything to C++11 to make this work. Is there any other way by which I can write this code which does not use C++11?Update:-
This is the way I am getting current timestamp in milliseconds in that big project at some part of the code -
struct timeval tp; gettimeofday(&tp, NULL); uint64_t current_ms = tp.tv_sec * 1000 + tp.tv_usec / 1000; //get current timestamp in milliseconds