Thread: Strcmp causes segmentation fault

I'm currently doing a hash search program. Here is the following code.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#define M 12
#define N 467 

/*
size of hash table is 467
Which is a prime number and in form of 4(j)+3
j=116
4*116+3=467
So suitable for square probe hashing
*/

typedef struct student{
    char name[50];
    char sex[10];
    char number[M];
}ST;

void initTable(ST *A);
void readFromFile(ST *A);
int hashFun(char *number);
void query(ST *A, char *number);//search
int getPrime(int n);

void initTable(ST *A){
    for(int i=0;i<N;i++){
        strcpy(A[i].name,"-");
        strcpy(A[i].sex,"-");
        strcpy(A[i].number,"-");
    }
}

int hashFun(char *number){
    /*FOLDING METHOD*/
    /*3digit+3digit+3digit+2*/
    int temp,hashNum=0;
    for(int i=0;i<M-2;i++){
        temp=0;
        temp+=(number[i]-'0');
        if(i+1<M-1){
            temp*=10;
            temp+=(number[++i]-'0');
            if(i+1<M-1){
                temp*=10;
                temp+=(number[++i]-'0');
            }
        }
        hashNum+=temp;
    }
    //printf("%s\t%d\t%d\n",number,hashNum,hashNum%N);
    return hashNum%N;
}

void readFromFile(ST *A){
    ST temp;
    FILE *file;
    file = fopen("data4.txt","r");
    int rehash=0;
    while(fscanf(file,"%s %s %s",temp.name,temp.sex,temp.number)>0){
        int index=hashFun(temp.number);
        int tempRehash=0;
        if(A[index].number[0]=='-'){
            strcpy(A[index].name,temp.name);
            strcpy(A[index].sex,temp.sex);
            strcpy(A[index].number,temp.number);
        }
        else{
            int n=1;
            int tempIndexLeft=index-(n*n)%N;
            int tempIndexRight=index+(n*n)%N;
            while( !(A[tempIndexLeft].number[0]=='-' || A[(tempIndexRight)%N].number[0]=='-' ) ){
                n++;
                tempIndexLeft=index-(n*n)%N;
                tempIndexRight=index+(n*n)%N;
                tempRehash++;
            }
            if(A[(index+(n*n))%N].number[0]=='-')
                index=(index+(n*n))%N;
            else
                index=(index-(n*n))%N;
            strcpy(A[index].name,temp.name);
            strcpy(A[index].sex,temp.sex);
            strcpy(A[index].number,temp.number);      
        }
        if(rehash<tempRehash)
            rehash=tempRehash;
    }
    printf("\nHash table built successfully.\n");
    printf("Maximum rehash time: %d\n",rehash);
    
}

void query(ST *A, char *number){
    printf("test");
    char exitCondition[]="-";
    int index=hashFun(number);
    int rehash =0; //+1 for first hash later
    //int boolFound=0;//current false

    int tempIndexLeft=index-(rehash*rehash)%N;
    int tempIndexRight=index+(rehash*rehash)%N;
    printf("%d\t%d",tempIndexLeft,tempIndexRight);
    while( !(strcmp(A[tempIndexLeft].number,number)==0 || strcmp(A[tempIndexRight].number,number)==0) ){
        rehash++;
        //printf("test");
        if(strcmp(A[tempIndexLeft].number,"-")!=0)
            tempIndexLeft=index-(rehash*rehash)%N;
        if(strcmp(A[tempIndexRight].number,"-")!=0)
            tempIndexRight=index+(rehash*rehash)%N;
        
        if(strcmp(A[tempIndexLeft].number,exitCondition)==0 && strcmp(A[tempIndexRight].number,exitCondition)==0)
            break;
    }

    printf("After %d time(s) hash,",rehash+1);
    if(strcmp(A[tempIndexLeft].number, number)==0){
        printf("Record found:\n%s %s %s\n",A[tempIndexLeft].name,A[tempIndexLeft].sex,A[tempIndexLeft].number);
    }
    else if(strcmp(A[tempIndexRight].number, number)==0){
        printf("Record found:\n%s %s %s\n",A[tempIndexRight].name,A[tempIndexRight].sex,A[tempIndexRight].number);
    }
    else{
        printf("Record not found.\n");
    }
    
}

int main(){
    ST A[N];
    char phoneNumberInput[M];
    char exitConditon[]={"0"};
    initTable(A);
    readFromFile(A);

    //for(int i=0;i<N;i++){
    //    printf("%s %s %s\n",A[i].name,A[i].sex,A[i].number);
    //}
    //if(strcmp(A[0].number,"13267729168")==0)
    //    printf("True");
    while(1){
        printf("\nPlease input phone number: ");
        scanf("%s",phoneNumberInput);
        printf("test");
        if(strcmp(phoneNumberInput,exitConditon)==0)
            break;
        printf("test");
        query(A,phoneNumberInput);
    }
}

data4.txt
and this is the input that cause that segmentation fault:
18638110371
There are some other input that causes the same problem.
GDB shows that the query were actually called, but I put some printf("test") and it wont print on the console. And gdb cannot show tempIndexLeft and tempIndexRight value at all.

You need an zero terminated character array to use as an C-String!

so make it

Code:

exitCondition[]={'0','\0'} ?

It does not fix the problem

When I ran the code in VS 2019 I got an exception at line 85

Code:

strcpy(A[index].name, temp.name);

when index was -307.