feat: update code for strings

Author: mcps5601

07-Strings-2/modify_str.c

@@ -0,0 +1,11 @@
+#include <stdio.h>
+int main(void){
+    char a_string[] = "Sweet home";
+    char *ptr1 = a_string;
+    char *ptr2 = "Sweet home";
+    *(ptr1+6) = 'd';
+    *(ptr2+6) = 'd'; // This line causes an error!
+    for (int i = 0; i < 10; i++){
+        printf("%c", ptr1[i]);
+    }
+}

07-Strings-2/print_str_via_ptr.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+int main(void){
+    char a_string[] = "Sweet home"; 
+    char *ptr = a_string;
+    for (int i = 0; i < sizeof(a_string); i++){
+        printf("%c", *(ptr + i));
+    }
+}
+
+    // while(*ptr != '\0'){
+    //     printf("%c", *ptr);
+    //     ptr++;
+    // }

07-Strings-2/str_ptr_subscripting.c

@@ -0,0 +1,8 @@
+#include <stdio.h>
+int main(void){
+    char a_string[10] = "Sweet home"; 
+    char *ptr = a_string;
+    for (int i = 0; i < sizeof(a_string); i++){
+        printf("%c", ptr[i]);
+    }
+}

07-Strings-2/subscripting.c

@@ -0,0 +1,9 @@
+#include <stdio.h>
+int main(void){
+    int arr[5] = {1, 2, 3, 4, 5};
+    int *p = &arr[0];
+    printf("arr[0] = %d\n", arr[0]);
+    printf("p[0] = %d\n", p[0]);    // *(p + 0)
+    printf("arr[1] = %d\n", arr[1]);
+    printf("p[1] = %d\n", p[1]);    // *(p + 1)
+}