String alapok

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

//sajat fuggveny deklaracio
int karakterszamolo(char *p);
void nagybetuvelir(char *p);
void forditvair(char *p);
int main(void)
{
    char *p;
    p = "This is a test string.";
    char *start = p;
    char str[ ] = "This is a test string.";
    int i;
    char *str_start = str;
    printf("The text: %s\n", p);
    int hossz = karakterszamolo(p);
    /*int db = 0;
    while(*p) {
        db++;
        p++;
    }//Itt a p poiter a szoveg vegere mutat*/
    printf("The length of the text: %d\n", hossz);
    //p =start;
    printf("The text: %c\n", *p);
    printf("Nagybetuvel:");
    nagybetuvelir(p);
    /*
    while(*p){
        printf("%c", toupper(*p));
        p++;
    }*/
    printf("\nThe text: %s\n", p); // Eredeti szoveg
/*
    for(i=0; str[i]!='\0'; i++);{
        str[i] = toupper(str[i]);
    }// A pointer a szoveg vegere mutat
    //str = str_start;
    printf("\nThe text: %s\n", str);*/
    forditvair(p);
    return 0;
}

// sajat fuggveny definicio
int karakterszamolo(char *p){
    int db = 0;
    while(*p){
        db++;
        p++;
    }
    return db;
}

void nagybetuvelir(char *p){
    while(*p){
        printf("%c", toupper(*p));
        p++;
    }
    return ;
}

void forditvair(char*p){
    printf("\nMegforditva:\n");
    while(*p) p++;
    p--;
    while(*p){
            printf("%c", *p);
        p--;
    }
    return ;
}