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

void upperCase(char *s);
size_t strlen(const char *s);
void printArrChar(char a[], int arr_size);

int main()
{
    char *myString = "this is a string in c";
    upperCase(myString);
    printf("%s\n", myString);
}

void upperCase(char *s){
    int i=0;
    size_t len = strlen(s)+1;
    char charArray[len];
    while (*(s+i) != '\0'){
        if (*s >=97 && *s <= 122){
            charArray[i] = *(s+i) -32;
        }
        else
        {
            charArray[i] = *(s+i);
        }
        i++;
    }
    charArray[len-1] = '\0';
    // printArrChar(charArray, sizeof(charArray)/sizeof(charArray[0]));
    memcpy(s, &charArray, len);
}

size_t strlen(const char *s){
    size_t i = 0;
    while (*(s+i) != '\0'){
        i++;
    }
    return i;
}

void printArrChar(char a[], int arr_size){
    int i;
    for(i=0; i<arr_size; i++){
        printf("%c\n", a[i]);
    }
}