Подскажите, пожалуйста, верно ли решение.

#include <iostream>
 
using namespace std;
 
int main ()
{
cout << "What is your first name? ";
char *first = new char[20];
cin.get(first,20); 
cin.get();
cout << "What is your last name? ";
char *last = new char[20];
cin.get(last,20);
cin.get();
cout << "What letter grade do you deserve? ";
 
 
char piz; //Очень сомневаюсь в правильности здесь
int pizint;
cin >> piz;
pizint=piz;
pizint = pizint+1;
piz=pizint;
 
 
cout << "What is your age? ";
int *age = new int;
cin >> *age;
 
cout << "Name: " << first << " " << last << endl;
cout << "Grade:" << piz << endl << "Age: " << *age; 
 
 delete [] first;
 delete [] last;
 delete age;
 
 
    cout << endl;
    system("PAUSE");
    return 0;
}

piz += 1;

++piz;

#include <iostream>
#include <string>
 
using namespace std;
 
int main ()
{
cout << "What is your first name? ";
string first;
cin >> first; 
cout << "What is your last name? ";
string last;
cin >> last;
cout << "What letter grade do you deserve? ";
 
 
string piz; 
 
cin >> piz;
// Cделать обработку случая, когда ввели что-то отличное от одной буквы. 
int pizint = int (piz[0]);
piz[0]=char(++pizint);
 
 
cout << "What is your age? ";
string age;
cin >> age;
// Сделать обработку  случая когда ввели не натуральное число. 
cout << "Name: " << first << " " << last << endl;
cout << "Grade: " << piz << endl << "Age: " << age << endl; 
    system("PAUSE");
    return 0;
}

cout << "What is your first name? ";
string first;
getline(cin, first);
 
cout << "What is your last name? ";
string last;
getline(cin, last);

#include <stdio.h>
#include <conio.h>
 
int main()
{
    int age;
    char first[32] = {0}, last[32] = {0}, grade;
    printf("What is your first name? ");
    scanf("%[^\n]%c",first,&grade);
    printf("What is your last name? ");
    scanf("%[^\n]%c",last,&grade);
    printf("What letter grade do you deserve? ");
    scanf("%c",&grade);
    printf("What is your age? ");
    scanf("%d",&age);
 
    printf("Name : %s, %s\r\n",last,first);
    printf("Grade: %c\r\n",(grade + 1));
    printf("Age  : %d\r\n",age);
    printf("Press any key to continue\r\n");
    getch();
    return 0;
}

int *age = new int[1];

...
cout << "What letter grade do you deserve? ";
char piz;
cin >> piz;
++piz;
...

#include <stdio.h>
#include <conio.h>
 
enum GRADE {A = 'B',B,C,D,E,F = 'A'} GRADE;
 
int main()
{
    int age;
    char first[32] = {0}, last[32] = {0}, grade;
    printf("What is your first name? ");
    scanf("%[^\n]%c",first,&grade);
    printf("What is your last name? ");
    scanf("%[^\n]%c",last,&grade);
    printf("What letter grade do you deserve? ");
    scanf("%c",&grade);
    printf("What is your age? ");
    scanf("%d",&age);
 
    printf("Name : %s, %s\r\n",last,first);
//  printf("Grade: %c\r\n",(grade + 1));
    enum GRADE pGRADE;
    switch(grade){
    case 'A':
        pGRADE = A;
        break;
    case 'B':
        pGRADE = B;
        break;
    case 'C':
        pGRADE = D;
        break;
    case 'D':
        pGRADE = D;
        break;
    case 'E':
        pGRADE = E;
        break;
    case 'F':
        pGRADE = F;
        break;
    }
    printf("Grade: %c\r\n",pGRADE);
    printf("Age  : %d\r\n",age);
    printf("Press any key to continue\r\n");
    getch();
    return 0;
}

#include <stdio.h>
#include <conio.h>
 
int main()
{
    int age;
    char first[32] = {0}, last[32] = {0}, grade;
    printf("What is your first name? ");
    scanf("%[^\n]%c",first,&grade);
    printf("What is your last name? ");
    scanf("%[^\n]%c",last,&grade);
    printf("What letter grade do you deserve? ");
    scanf("%c",&grade);
    printf("What is your age? ");
    scanf("%d",&age);
 
    printf("Name : %s, %s\r\n",last,first);
    switch(grade){
    case 'A':
        grade = 'B';
        break;
    case 'B':
        grade = 'C';
        break;
    case 'C':
        grade = 'D';
        break;
    case 'D':
        grade = 'E';
        break;
    case 'E':
        grade = 'F';
        break;
    default:
        grade = 'A';
        break;
    
    }
    printf("Grade: %c\r\n",grade);
    printf("Age  : %d\r\n",age);
    printf("Press any key to continue\r\n");
    getch();
    return 0;
}

#include <iostream>
#include <cctype>
 
using namespace std;
 
int main()
{
    cout << "What letter grade do you deserve? ";
    char piz;
    cin >> piz;
    char const *grades = "ACBA";
 
    int idx = 1;
    while (grades[idx] && grades[idx] != toupper(piz))
        ++idx;
 
    cout << grades[idx - 1] << endl;
 
    return 0;
}

#include <stdio.h>
#include <conio.h>
  
int main()
{
        int age;
        char first[32] = {0}, last[32] = {0}, grade;
        printf("What is your first name? ");
        scanf("%[^\n]%c",first,&grade);
        printf("What is your last name? ");
        scanf("%[^\n]%c",last,&grade);
        printf("What letter grade do you deserve? ");
        scanf("%c",&grade);
        printf("What is your age? ");
        scanf("%d",&age);
        printf("Name : %s, %s\r\n",last,first);
        if (grade == 'F') grade = 'A' -1   ;
        printf("Grade: %c\r\n", ++grade);
        printf("Age  : %d\r\n",age);
        printf("Press any key to continue\r\n");
        getch();
        return 0;
}