Function stoi not declared

Question

I m trying to use stoi to convert a string to an integer  however it says it s not declared  I have the standard library and the  lt string gt  included  but it still says  Error   stoi  was not declared in this scope  The code is the following    include  lt iostream gt   include  lt stdio h gt   include  lt stdlib h gt   include  lt string gt   using namespace std   int main     string end  init  cout  lt  lt   Introduction   lt  lt  endl  cout  lt  lt   Start time  xx yy    lt  lt  endl  cin  gt  gt  init  string hours0   init substr 0 2   int hours   stoi hours0   cout  lt  lt  hours  lt  lt  endl  system  pause    return 0       Either tell me why it isn t working  or give me a second option to do it  please

User · Answer

Add this option  -std c  11 while compiling your code  g   -std c  11 my cpp code cpp

User · Answer

stoi is a C  11 function  If you aren t using a compiler that understands C  11  this simply won t compile   You can use a stringstream instead to read the input   stringstream ss hours0   ss  gt  gt  hours

User · Answer

std  stoi was introduced in C  11  Make sure your compiler settings are correct and or your compiler supports C  11

User · Answer

In comments under another answer  you indicated you are using a dodgy version of g   under MS Windows   In this case  -std c  11 as suggested by the top answer would still not fix the problem   Please see the following thread which does discuss your situation  std  stoi doesn  39 t exist in g   4 6 1 on MinGW

User · Answer

instead of this line -   int hours   stoi hours0    write this -   int hours   atoi hours0 c str      Reference    int atoi const char  str

User · Answer

The answers above are correct  but not well explained    g   -std c  11 my cpp code cpp   Add -std c  11 to your compiler options since you are most likely using an older version of debian or ubuntu which is not using by default the new c  11 standard of g   gcc  I had the same problem on Debian Wheezy    http   en cppreference com w cpp string basic string stol  shows in really small writing to the right in green that c  11 is required

User · Answer

I came across this error while working on a programming project in c      atoi   stoi   is not part of the old c   library in g   so use the below options while compiling g   -std c  11 -o my app code my app code cpp Include the following file in your code   include  lt  cstdlib     This should take care of the errors

User · Answer

include  lt algorithm gt    Include this and then you can compile it using     g   -Wall -std c  11 test cpp -o test  You can also add  cd  d   dp0  as the first line of a  bat file in the same directory as your source file so all you have to do is double click on the  bat file for an  automated  compilation   Hope this helps

User · Answer

Install the latest version of TDM-GCC here is the link-http   wiki codeblocks org index php MinGW installation

User · Answer

stoi is available  since C  11    Make sure your compiler is up to date   You can try atoi hours0 c str    instead

User · Answer

I managed to fix this problem by adding the following lines to my CMakeLists txt   set CMAKE C FLAGS    CMAKE C FLAGS   -Wall  -O3 -march native    set CMAKE CXX FLAGS    CMAKE CXX FLAGS  -Wall   -O3 -march native      Check C  11 or C  0x support include CheckCXXCompilerFlag  CHECK CXX COMPILER FLAG  -std c  11  COMPILER SUPPORTS CXX11  CHECK CXX COMPILER FLAG  -std c  0x  COMPILER SUPPORTS CXX0X  if COMPILER SUPPORTS CXX11     set CMAKE CXX FLAGS    CMAKE CXX FLAGS  -std c  11      add definitions -DCOMPILEDWITHC11     message STATUS  Using flag -std c  11    elseif COMPILER SUPPORTS CXX0X     set CMAKE CXX FLAGS    CMAKE CXX FLAGS  -std c  0x      add definitions -DCOMPILEDWITHC0X     message STATUS  Using flag -std c  0x    else      message FATAL ERROR  The compiler   CMAKE CXX COMPILER  has no C  11 support  Please use a different C   compiler    endif     As mentioned by the other fellows  that is the -std c  11 issue

User · Answer

Are you running C   11  stoi was added in C   11  if you re running on an older version use atoi

[c++] Function stoi not declared

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