Programme en c

unsigned int read_unsigned_int(char *mot){
  unsigned short int n=0;
  unsigned int res=0;
  while( sscanf(mot,"%d",&n) == 1 ){
    res*=10;
    res+=n;
  }
  return res;
}

#include <string.h>
#define ERR 0

unsigned short int ctoi(char c){
  if(c>=48 && c <=57){
    return c-48; // conversion ascii --> decimal
  }
  printf("ctoi : caractère %c invalide... retourne %d\n",c,ERR);
  return ERR;
}

unsigned int read_unsigned_int(char *mot){
  unsigned int i,res=0,len=strlen(mot);
  unsigned short int n;
  for(i=0;i<len;++i){
    res*=10;
    n=ctoi(mot[i]);
    if(n==ERR){
      printf("atoi : chaine %s invalide... retourne %d\n",mot,ERR);
      return ERR;
    }
    res+=n;
  }
  return res;
}