read last column of the file and compare the data using c

I have to modify the data in the file using c program.
Flow process
1. Read the file and find the section using string compare function.
2. In that section, read the last column of the data.
3. Compare the data with input, if both are same change that specific value.

1. In example input, element section row 4-6 last column value is "2" after the process the example output value is changed from 2 to "4"
2. and row 7-9 last column value is "3" after the process the example output value is changed from 3 to "2"

For example
-if User input ="2" and the last column value of the line also "2"
- then change that value to "4" as it is shown in example input and output file

inputfile sample
Coordinates
Elements
1 1 2 3 4 5 6 7 8 1
2 4 3 9 10 8 7 11 12 1
3 10 9 13 14 12 11 15 16 1
4 14 13 17 18 16 15 19 20 2
5 18 17 21 22 20 19 23 24 2
6 22 21 25 26 24 23 27 28 2
7 26 25 29 30 28 27 31 32 3
8 30 29 33 34 32 31 35 36 3
9 34 33 37 38 36 35 39 40 3
End_elements
End_Coordinates

output file sample

Coordinates
Elements
1 1 2 3 4 5 6 7 8 1
2 4 3 9 10 8 7 11 12 1
3 10 9 13 14 12 11 15 16 1
4 14 13 17 18 16 15 19 20 4
5 18 17 21 22 20 19 23 24 4
6 22 21 25 26 24 23 27 28 4
7 26 25 29 30 28 27 31 32 2
8 30 29 33 34 32 31 35 36 2
9 34 33 37 38 36 35 39 40 2
End_elements
End_Coordinates

I have tried to write program to do this process but, i don't know how to read last column and do the comparison process.
i have tried to write program to perform change in value but i failed. please suggest me the process to finish this operation
my code is given here'


code sample

Code:

---


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

#define END_ELEMENTS  "END_ELEMENTS "
#define ELEMENTS "ELEMENTS "

FILE*file1;
FILE*out1;

voidOpenInputFile();
intExtract_Node_value(char*To_Find_node,char*To_Element_set_list);


int main()
{
  double result;

  OpenInputFile();

  out1 = fopen("out.txt","w");
    if(out1 == NULL)
    {
      perror("fopen");
      exit(EXIT_FAILURE);
    }

      result =Extract_Node_value(ELEMENTS, END_ELEMENTS);
      printf("%s", result);
      fclose(file1);
      fclose(out1);

    return0;
}// end main

intExtract_Node_value(char*To_Find_node,char*To_Element_set_list)
{
  char line[256];
  char line1[256];

  intCompare_value=2;
  intChange_value=4;

  int word;
  int fword;

      if(!file1){
      perror("fopen");
      exit(EXIT_FAILURE);
      }

      while(fgets(line,sizeof(line),file1)){
          // fprintf(out1, " %s ", line);
          if(!strstr(line,To_Find_node)){
            continue;
          }

          while(fgets(line,sizeof line,file1)){
          printf("%s \n", line);
          fprintf(out1,"%s", line);

              while(sscanf(line,"%d%*[^\n]",&fword)){

      /// i have tried to write program to perform change in value but i failed
    please suggest me the process to finish this operation

                  fgets(line,sizeof line,file1);
                    if(strstr(line,To_Element_set_list)){
                        return0;
                    }
                      fprintf(out1,"%s", line);

          }
      }
  }
      return0;
}

 voidOpenInputFile(){

  file1 = fopen("input.txt","r");

 /// check if file exists
  if(!file1){

  perror("fopen");
  exit(EXIT_FAILURE);
  }

 return;

}

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