I think it's because I use int and I should use long to avoid overflow... for the number I want to display:

void loop() 
{
 for(int i=0;i<100000;i++)
 {
   afficher_nombre(i);
   delay(5);
 }
}

should be :

void loop() 
{
 for(long i=0;i<100000;i++)
 {
   afficher_nombre(i);
   delay(5);
 }
}

I think it's because I use int and I should use long to avoid overflow... for the number I want to display:

void loop() 
{
 for(int i=0;i<100000;i++)
 {
   afficher_nombre(i);
   delay(5);
 }
}

should be :

void loop() 
{
 for(long i=0;i<100000;i++)
 {
   afficher_nombre(i);
   delay(5);
 }
}

And also a parentheses problem solved thanks to cattledog on this forum