Bài 2:

#include<stdio.h>

#include<string.h>

main()

{

int a[20],choice,n,i=0,j,tam;

char st[20];

//Hiển thị menu

printf("\n******************************************");

printf("\n* Ho ten: *");

printf("\n* Ngay sinh: *");

printf("\n* Ma so: *");

printf("\n* 1. Doi so thap luc phan *");

printf("\n* 2. In phu am ra man hinh *");

printf("\n* 3. Thoat *");

printf("\n******************************************");

printf("\nMoi ban nhap vao mot so:");

scanf("%d",&choice);

//Doi so thap luc phan

if(choice==1)

{

printf("Nhap so thap phan:");

scanf("%d",&n);

while(n!=0)

{

a[i]=n%16;

n=n/16;

i++;

}

printf("He 16 la:");

for(j=i-1;j>=0;j--)

{

if(a[j]==10)

printf("A");

else if(a[j]==11)

printf("B");

else if(a[j]==12)

printf("C");

else if(a[j]==13)

printf("D");

else if(a[j]==14)

printf("E");

else if(a[j]==15)

printf("F");

else

printf("%d",a[j]);

}

}

//in phu am ra man hinh

else if(choice==2)

{

{

printf("Nhap vao mot chuoi:");

scanf("%s",st);

strcat(st,"\n");

for(i=0;i<strlen(st);i++)

{

if((st[i]=='a')|| (st[i]=='e')||(st[i]=='i')||(st[i]=='o')||(st[i]=='u')||

(st[i]=='A')||(st[i]=='E')||(st[i]=='I')|| (st[i]=='O')||(st[i]=='U'))

continue;

else

if(((st[i] >= 'a') && (st[i] <= 'z'))||((st[i]>='A') && (st[i]<='Z')))

printf("%c",st[i]);

}

}

}

else

{

exit(1);

}

getch();

}