File reading and concatenating

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

int concat(char* input_path1, char* input_path2, char* output_path)
{
    FILE *input_file1;
    FILE *input_file2;
    FILE *output_file;
    int c;

    output_file = fopen(output_path, "w");
    input_file1 = fopen(input_path1, "r+");

    while((c = fgetc(input_file1)) != EOF)
    {
        printf("%c", (char)c);
        fprintf(output_file, "%c", (char)c);
    }

    fclose(input_file1);
    input_file2 = fopen(input_path2, "r+");

    while((c = fgetc(input_file2)) != EOF)
    {
        printf("%c", (char)c);
        fprintf(output_file, "%c", (char)c);
    }

    fclose(input_file2);
    fclose(output_file);
}

char* lirechar()
{
    int n=0;
    char *c=(char*)malloc(1);
    char saisie=getchar();
    while(saisie!='\n')
    {
        c[n]=saisie;
        saisie=getchar();
        n++;
        c=(char*)realloc(c,n+1);
    }
    c[n]='\0';
    return c;

}


int main()
{
    char* input_path1;//={'1','.','t','x','t'};
    char* input_path2;//={'2','.','t','x','t'};
    char* output_path;//={'3','.','t','x','t'};

    input_path1=lirechar();
    input_path2=lirechar();
    output_path=lirechar();

    concat(input_path1, input_path2, output_path);

    return 0;
}