PPN1

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

char * to_String(int n) {
    char temp[11] = { 0 };
    char res[11] = { 0 };
    int j = 0;
    while (n > 0) {
        temp[j] = n % 10 + '0';
        n /= 10;
        j++;
    }
    for (int i = 10; i > 0; i--) {
        res[i] = temp[10 - i];
    }
    return res;
}

char * to_string(int n) {
     int m = n;
     char s[11];
     char ss[11];
     int i=0,j=0;
     if (n < 0)// Handling negative numbers
     {
         m = 0 - m;
         j = 1;
         ss[0] = '-';
     }
     while (m>0)
     {
         s[i++] = m % 10 + '0';
         m /= 10;
     }
     s[i] = '\0';
     i = i - 1;
     while (i >= 0)
     {
         ss[j++] = s[i--];
     }
     ss[j] = '\0';
     return ss;
}

int ppn(char *op, char *e, char *w) {
    if ((e[0] >= '0' && e[0] <= '9') && (w[0] >= '0' && w[0] <= '9')) {
        if (op == '/') {
            return atoi(e) / atoi(w);
        }
        else {
            return atoi(e) * atoi(w);
        }
    }
    if ((e[0] >= '0' && e[0] <= '9') && (w[0] == '/' || w[0] == '*')) {
        char t1[11], t2[11];
        scanf(" %s %s", &t1, &t2);
        if (op == '/') {
            return atoi(e) / ppn(w[0], t1, t2);
        }
        else {
            return atoi(e) * ppn(w[0], t1, t2);
        }
    }
    if ((e[0] == '/' || e[0] == '*') && (w[0] >= '0' && w[0] <= '9')) {
        char t1[11], t2[11];
        scanf(" %s %s", &t1, &t2);
        //fgets(t1, 11, stdin);
        return ppn(op, ppn(e[0], w, t1), t2); // op:/ e:/ w:100 2 2
    }
    if ((e[0] == '/' || e[0] == '*') && (w[0] == '/' && w[0] == '*')) {
        char t1[11], t2[11], t3[11], t4[11];
        scanf(" %s %s %s %s", &t1, &t2, &t3, &t4);
        //char ppn1[11] = itoa(ppn(w[0], t1, t2));
        //char ppn2[11] = itoa(ppn(e[0], ppn1, t3));
        return ppn(op, ppn(e[0], ppn(w[0], t1, t2), t3), t4);
    }
}

int main(void)
{
    char a, b[11], c[11];
    //scanf("%c %s %s", &a, b, c);
    //printf("%c %s %s", a, b, c);
    int n = 123;
    char * s = to_string(n);
    printf("%s", s);
    return 0;
}