Remove multiple/start/end spaces

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#define MAX_STR_LEN 64

int main(){
    char ch, string[MAX_STR_LEN], newstr[MAX_STR_LEN];
    int n=0, i, j=0;
    while((ch=getchar())!='$')
        string[n++]=ch;
    string[n]='\0';
    for(i=0;i<n;i++){
        if(isalnum(string[i]))
            newstr[j++]=string[i];
        else if(((isspace(string[i]))&&(isalnum(string[i+1])))&&(j!=0))
            newstr[j++]=' ';
    }
    newstr[j]='\0';
    printf("The resulting string is:\n%s\n", newstr);
    return 0;
}