在c++中编译模板结构

我使用c++模板开发了一个数组库来处理多种类型{int, float, double}。我将结构体和函数的定义和声明存储在Util.h和Util.cpp文件中。我在arraysample。cpp中调用它。但是，我无法编译该项目。c++说对printArray

错误信息

make all 
g++ -O2 -g -Wall -fmessage-length=0   -c -o arraySample.o arraySample.cpp
g++ -O2 -g -Wall -fmessage-length=0   -c -o Util.o Util.cpp
g++ -o arraySample arraySample.o Util.o 
arraySample.o: In function `main':
/home/vtvan/Desktop/workspace/arraySample/arraySample.cpp:15: undefined reference to `int printArray<double>(Array<double>)'
/home/vtvan/Desktop/workspace/arraySample/arraySample.cpp:22: undefined reference to `int printArray<int>(Array<int>)'
collect2: ld returned 1 exit status
make: *** [arraySample] Error 1

请帮我解决这个问题，我已经尝试了很多次，但无法解决它。很奇怪，当我将3个文件组合在一起时，它可以很好地工作。所以请给我一些解决方案。我在这里附上3个文件的源代码供您参考。

非常感谢，我期待着你的回复。

Util.h

#ifndef UTIL_H_
#define UTIL_H_
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <typeinfo>
#define ARRAYMAXNDIMS 3
// multi-dimensional array 
template <typename T>
struct Array {
   T *x;
   int size;
   int nDims;
   int N[ARRAYMAXNDIMS];
};
template <typename T> int printArray(Array<T> A);
#endif /* UTIL_H_ */  

Util.cpp

#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <typeinfo>
#include "Util.h"
template <typename T> int printArray(Array<T> A) {
  int i = 0, j = 0;
  int k,l;
  std::string typeT = typeid(T).name();
  std::string format("  %9f");
  if (!typeT.compare("i"))
          format = "  %d";
  printf("Array with dimension (%d",A.N[0]);
  k=1;
  while(k<A.nDims && k<ARRAYMAXNDIMS){
    printf(",%d",A.N[k]);
    k++;
  }
  printf(")n");
  switch (A.nDims) {
  case 1: // print 1D array
    for(k=0;k<A.N[0];k++){ printf("  %9d",A.x[k]);}
    printf("n");
    return(1);
  case 2: // print 2D array
    for(k=0;k<A.N[0];k++){
      for(l=0;l<A.N[1];l++) {
          printf(format.c_str(),A.x[k+l*A.N[0]]);
      }
      printf("n");
    }
    return(1);
  case 3: // print last 2 dimensions of a 3D array, where the index of the first dimension is i
    if(i<0 || i>=A.N[0]) {
      printf("index %d is outside the range of indices for the first dimension, i.e. [0:%d]n",i,A.N[0]-1);
      return(0);
    }
    printf("printing slice (%d,:,:)n",i);
    for(k=0;k<A.N[1];k++){
//      printf("%5d   ",k);
      for(l=0;l<A.N[2];l++) printf("  %9d",A.x[i+k*A.N[0]+l*A.N[0]*A.N[1]]);
      printf("n");
    }
    return(1);
  }
}

arraySample.cpp

#include <stdio.h>
#include <stdlib.h>
#include "Util.h"
int main(void) {
    Array<double> a;
    a.nDims = 2; a.N[0] = 2; a.N[1] = 2; a.size = 4;
    a.x = (double *)calloc(a.size,sizeof(double));
    a.x[0] = 1.23; a.x[1] = 2.23; a.x[2] = 3.23; a.x[3] = 5.23;
    printArray(a);
    Array<int>   b;
    b.nDims = 2; b.N[0] = 2; b.N[1] = 2; b.size = 4;
    b.x = (int *)calloc(b.size,sizeof(int));
    b.x[0] = 1; b.x[1] = 2; b.x[2] = 3; b.x[3] = 5;
    printArray(b);
        return 0;
}