修剪int字符串

 char buffer[20];
 char num[] = "2107900000";
 int j = 0;
 for (int i = 0; num[i]; i++)
 {
   if (num[i] != '0' && num[i] != '1')
   {
     buffer[j] = num[i];
     j++;
   }
 }
 buffer[j] = 0 //null terminator

 char num[] = "2107900000";
 int j = 0;
 for (int i = 0; num[i]; i++)
 {
   if (num[i] != '0' && num[i] != '1')
   {
     num[j] = num[i];
     j++;
   }
 }
 num[j] = 0 //null terminator

stripped orig

void strip_0s_and_1s(char *orig, char *stripped)
{
    // while we haven't seen a null terminator
    while(*orig){
        // if the current character is not a 1 or a 0...
        if(*orig != '0' && *orig != '1'){
           // copy the character
           *stripped= *orig;
           stripped++;
        }
        // increment pointer to old string
        orig++;
    }
    // terminate 'stripped' string
    *stripped= '\0';
}

#include <stdio.h>
#include <string.h>
int main (int argc, char **argv) {
    int len; 
    char str[100]; // max string length of 99+1 null terminator
    scanf("%s", str); 
    len = strlen(str);
    printf("%d", len); 
    return 0; 
}

new

for (i=j=0; s[i]=s[j]; i+=((unsigned)s[j++]-'0'>2));

i j j++ (unsigned)s[j++]-'0'>2 '0' '1'