问C代码中的浮点异常(核心转储)错误

EN

  #include<stdio.h>
int length(int a,int b);
int andop(int a,int b);
int main(){
    int first,sec;
    do{
        printf("First integer:  ");
        scanf("%d",&first);
        printf("\nSecond integer:  ");
        scanf("%d",&sec);} 
    while(andop(first,sec)==0); 
    printf("\n%d AND %d= %d",first,sec,andop(first,sec));
    return 0;
}

int andop(int a,int b){

   int a_1,b_1;
   int result=0;

    a_1=a;
    b_1=b;
    while(a_1>1){/*Checking if first is binary or not,the loop briefly checks if the number in each digits either 1 or 0,and if it dont returns 0 it also quit the loop and stop asking for new numbers*/
        if (a_1%10>1){
             printf("\nInteger should be binary,please enter 2 new integers\n");
             return 0; 
         }
     a_1=a_1/10; 
    }   
    while(b_1>1){/*Checking if first is binary ,the loop briefly checks if the number in each digits either 1 or 0,and if it dont returns 0 it also quit the loop and stop asking for new numbers*/
        if (b_1%10>1){
            printf("\nInteger should be binary,please enter 2 new integers\n");
            return 0;
      }
      b_1=b_1/10; 
    }

    while (length(a,b)>0){ 

    result=result+(a%10)*(b%10);  
    a=a/10;
    b=b/10;
    if(length(a,b) == 0){
    break;
    }
    result=result*10;
    }
    return result;
    }

 int length(int a,int b){
   if(a == 0 || b == 0){
    return 0;
   }
   int temp_a,temp_b;
   int length_a=0,length_b=0;

   temp_a=a;/*i assign the number into the temporary variable _a and _b*/ 
   temp_b=b;
   while(temp_a>0){//checking how many digit a is
        temp_a=temp_a/10;
        length_a++;
   }
   while(temp_b>0){//checking how many digit b is
        temp_b=temp_b/10;
        length_b++;
   }

   if(length_!=length_b){/* If they don't have same digits ,print an error message and continue to taking number from user*/
         printf("\nInteger should have same length,please enter 2 new integers\n");
         return 0;
     }   

   return length_a;

}