#include <stdio.h>
#include <string.h>
 
int main(void)
{
    char name[] = "Pejman";
 
    printf("Name: %s\n", name);
    printf("Size: %d\n", sizeof(name));
    printf("Len : %d\n", strlen(name));
 
    return 0;
}

Name: Pejman
Size: 7
Len : 6

#include <stdio.h>
 
int main(void)
{
    char str[] = "Hello";
    str[0] = 'A';
    printf("%s\n", str);
 
    char *p = "Hello";  // gets stored as compile-time constant (.text)
    p[0] = 'A';         // Illegal - Segmentation fault
    printf("%s\n", p);
 
    return 0;
}

Aello
Segmentation fault

#include <stdio.h>
 
void f(char *c)
{
    c++;
    c[0] = 'A';
}
 
int main(void)
{
    char str[] = "Hello";
    f(str);
    printf("%s\n",str);
    return 0;
}

HAllo