diff --git a/primef.h b/primef.h
new file mode 100644
index 0000000000000000000000000000000000000000..21ebd732b0ed226a17f87e8f6f3676b8aa54e7ed
--- /dev/null
+++ b/primef.h
@@ -0,0 +1,39 @@
+//
+// Created by Louis Malevez on 19-04-20.
+//
+
+#ifndef PROJET_Q4_GROUPE_O4_PRIMEF_H
+#define PROJET_Q4_GROUPE_O4_PRIMEF_H
+# include <stdio.h>
+# include <math.h>
+int primeFactors(int n, FILE*f_out);
+
+
+int primeFactors(int n,FILE*f_out){// prends un fichier et écrit un entier et ses diviseurs dedans
+    int count1=0;
+    int count2=0;
+    fprintf(f_out,"%d ",n);
+    while (n%2 == 0)
+    {
+        if(count1==0) fprintf(f_out,"%d ", 2);
+        n = n/2;
+        count1+=1;
+    }
+    for (int i = 3; i*i <= n; i = i+2)
+    {
+        while (n%i == 0){
+
+            if(count2==0) fprintf(f_out,"%d ", i);
+            n=n/i;
+            count2+=1;
+        }
+        count2=0;
+    }
+    if (n > 2)
+        fprintf (f_out,"%d ", n);
+    fprintf(f_out,"\n");//passe à la ligne qd c'es terminé
+    return 0;
+}
+
+
+#endif //PROJET_Q4_GROUPE_O4_PRIMEF_H