将两个有序文本文件合并到另一个而不破坏C中的顺序

Question

I have two text file as;

Andrew Hall
Arnold Price
Shelley Baker

and,

Arnold Hill
Veronica Clay

As you can see they are ordered. I need to combine them into another text file which is ordered again. So, expected output is;

Andrew Hall
Arnold Hill
Arnold Price 
Shelley Baker
Veronica Clay

However, the output shows up as;

Andrew Hall
Arnold Hill
Arnold Price

I think somehow I am losing last lines of both files and both fsort1 and fsort2 reach end of their files. How can I find a general solution? What am I doing wrong?

My code is like that;

fgets(name1, 100, fsort1); 
fgets(name2, 100, fsort2);

while(!feof(fsort1) || !feof(fsort2)){
    if(strcmp(name1, name2)<0){
        fprintf(foutput, "%s", name1);
        fgets(name1, 100, fsort1);
    }
    else{
        fprintf(foutput, "%s", name2);
        fgets(name2, 100, fsort2);
    }
}

Thank you.

Answer 1

I think somehow I am losing last lines of both files and both fsort1 and fsort2 reach end of their files.

Yes, you are. The comments already pointed out the wrong use of feof , but if your loop stops because only one of the file is ended, you are not continuing the read the other file. You can use somthing like this:

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


int main(void)
{
    FILE *fsort1 = fopen("names1.txt", "r");
    FILE *fsort2 = fopen("names2.txt", "r");
    FILE *foutput = fopen("names_out.txt", "w");

    if ( !fsort1 || !fsort2 || !foutput)
    {
        perror("Error openng files");
        exit(EXIT_FAILURE);
    }

    char name1[256] = {'\0'};
    char name2[256] = {'\0'};
    char *r1 = fgets(name1, 256, fsort1);
    char *r2 = fgets(name2, 256, fsort2);

    while ( r1 && r2 )
    {
        if ( strcmp(name1, name2) < 0 ) {
            fprintf(foutput, "%s", name1);
            r1 = fgets(name1, 256, fsort1);
        }
        else {
            fprintf(foutput, "%s", name2);
            r2 = fgets(name2, 256, fsort2);
        }
    }
    while ( r1 )
    {
        fprintf(foutput, "%s", name1);
        r1 = fgets(name1, 256, fsort1);        
    }
    while ( r2 )
    {
        fprintf(foutput, "%s", name2);
        r2 = fgets(name2, 256, fsort2);        
    }        
}