#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct node {string car ; struct node * cdr ; } node, *list ;
#define nil NULL
#define car(node) ((node)->car)
#define cdr(node) ((node)->cdr)
#define BUFSIZ 100
typedef char* string
void usage(char *)
void libere (list L);

int main(int argc, char* argv[])
  {

	FILE *in, *out;
    in = fopen( argv[3], "r" );
    out= fopen( argv[4], "w" );

    if (in == NULL || out == NULL)
    printf ("erreur d'ouverture")

    list L1 = NULL;
    while (fgets(temp, BUFSIZ, in))
    {    L1 = cons(temp, L1) ;
        printf("%s", temp) ; }
    L2 = L1;
    list L2 = remplace(argv[1], argv[2], L1);
    L3 = L2;
    while ( L3 != NULL ) {
		fputs(car(L3), out);
		fputc ('\n', out)
   L3 = cdr ( L3 );
}
fclose(in);
fclose(out);
    return 0;
   }


list cons(int car, list L)
  {
    list new = malloc(sizeof(node)) ;
    if (! new) usage("manque de RAM") ;
    new -> car = car ;
    new -> cdr = L
    }

list remplace(string element, string par, list L)
{
    if (strcmp(car(L), element) == 0)
    {
        car(L) = par;
        return (cdr(L)==NULL)?L:remplace(element, par, cdr(L)) ;
    }
    if (L)
        return (cdr(L)==NULL)?L:remplace(element, par, cdr(L)) ;
    return NULL ;
}

void libere (list L)  {
	list temp;
	while (L != NULL)
	{
		temp = cdr ( L );
		free ( L );
		L = temp;
	}
}
void usage(char * message) { fprintf(stderr, "%s\n", message) ; exit(1) ; }