Segfault在gtest中初始化堆栈上的参考变量

Question

I'm creating a test for my TwoDArray container and I'm getting a segfault. The TwoDArray object initializes fine on the heap but when I try to test it on the stack, I get a segfault. It uses a vector on the heap as the underlying container. I initialized a vector perfectly fine but the TwoDArray object gives a segfault as soon as it runs.

I've cut out the functions as I'm mostly concerned with initialization.

 21 template<typename T>
 22 class TwoDArray{
 23 
 24   private:
 25     int numRows;
 26     int numCols;
 27     std::vector<T> * vecPtr; // Underlying container
 28 
 29   public:
 30     TwoDArray(){ TwoDArray( DEF_ROW_SIZE, DEF_COL_SIZE ); }

 ...

 40     TwoDArray( int m, int n ):numRows(m), numCols(n),
 41                               vecPtr(new std::vector<T>(m*n)){ }

 ...

 43     /* Destructor that specifies the size of the 2D Array
 44      */
 45     ~TwoDArray(){ delete vecPtr; }
 ...

then the actual test:

  2 #include <vector>
  3 #include <gtest/gtest.h>
  4 #include "TwoDArray.hpp"
  5 
  6 class TestTwoDArray : public testing::Test{
  7   public:
  8 
  9     TwoDArray<int> arr1;
 10     std::vector<int> vec;
 11 
 12     virtual void SetUp(){
 14     }
 15 
 16     virtual void TestDown(){
 17     }
 18 };
 19 
 20 TEST_F( TestTwoDArray, validSizeTest ){
 21   //arr1 = TwoDArray<int>();
 22   
 24 }
 25 

 30 int main(int argc, char* argv[]){
 31   TwoDArray<int> arr1;
 32   testing::InitGoogleTest(&argc,argv);
 33   return RUN_ALL_TESTS();
 34 }

I have another class that creates the object fine on the heap. Here line 9 gives the segfault. But line 31 doesn't. Maybe I'm not understanding how to initialize something.

Answer 1

Your default constructor doesn't do what you think it does. It leaves the various member variables uninitialized, then creates a temporary TwoDArray object.

What you want for a delegating constructor is

TwoDArray(): TwoDArray( DEF_ROW_SIZE, DEF_COL_SIZE ) { }