c - "One or more output arguments not assigned during call to "input_4”是什么意思？

Question

#include "mex.h"
#include "string.h"

void mexFunction( int nlhs,mxArray *plhs[],int nrhs,const mxArray *prhs[])
{
  double out, out_1, out_2;
  out_1 = mxGetScalar(prhs[0]);
  out_2 = mxGetScalar(prhs[1]);
  out= out_1+out_2;
  mexPrintf("%f\n ", out);
  return;
 }

我编写了这个函数来对两个数字求和。它奏效了。

mex input_4.c input_4(1,2) 3.000000

但是当这个输出值被分配给命令窗口中的一个变量时它说错误..例如

b=input_4(1,2); 3.000000 One or more output arguments not assigned during call to "input_4". why it is not assigning the value of 3 to b. can anyone help me what it means? thanks in advance

Answer 1

您目前没有分配任何 MATLAB 可以识别的输出。您需要将输出分配给 plhs。以下是我的做法:

void mexFunction( int nlhs,mxArray *plhs[],int nrhs,const mxArray *prhs[])
{
  double out, out_1, out_2;
  out_1 = mxGetScalar(prhs[0]);
  out_2 = mxGetScalar(prhs[1]);
  out= out_1+out_2;
  if (nlhs == 1)
    plhs[0] = mxCreateDoubleScalar(out);
  else if (nlhs > 1)
    mexErrMsgIdAndTxt("mexFile:tooManyOutputs", "Too many outputs!");
  else
    mexPrintf("%f\n ", out);

  return;
 }