无法在C中打开文件

Question

这是我打开文件的代码，其中输入如下。 程序将读取文件并计算最后一列的平均值。但每次我运行该程序时，我都会得到一个输出，说“＃34;无法打开文件＆＃34;。我无法弄清楚代码的问题。

Input
3   11  12  05  1   8.7
3   11  11  56  143 8.6
3   11  13  01  163 8.9
3   10  18  05  1   7.3

#include <stdio.h>
#include <stdlib.h>

int main(void){
  FILE *myfile,*output_file;

  int month,day,timeHour,timeMinute,stnNumber;
  float temperature;
  float sumTemp=0;
  float AverageTemp=0;

  myfile=fopen("Input_file.txt","r");
  //read through line by line
  if(myfile==NULL){
    printf("Failed to open file\n");
    exit(1);
  }
  output_file=fopen("average_sum.txt","w");

  if(output_file==NULL)
  {
    printf("The file was not opened.");
    exit(1);
  }
  while(fscanf(myfile,"%d %d %d %d %d %.2f", 
        &month,&day,&timeHour,&timeMinute,&stnNumber,&temperature) != EOF){
    sumTemp+=temperature;
    AverageTemp=sumTemp/4;
    fprintf(output_file,"%.2f\n",AverageTemp);
  }
  fclose(myfile);
  fclose(output_file);
}