400 Câu hỏi trắc nghiệm lập trình C/C++ có đáp án và lời giải chi tiết

void main()
{
    int i = 5, k;
    if (i == 0)
        goto label;
label: printf("%d", i);
    printf("Hey");
    getch();
}

A. Hey

B. 5

C. 5Hey

D. Complie error

void main()
{
    printf("%d ", 1);
    goto l1;
    printf("%d ", 2);
l1:goto l2;
    printf("%d ", 3);
l2:printf("%d ", 4);
    getch();
}

A. 1 4

B. 1 2 3 4

C.  Syntax error

D. Syntax error

#include <conio.h>
#include <stdio.h>
void foo();
int main()
{
    printf("%d ", 1);
    goto l1;
    printf("%d ", 2);
}
void foo()
{ 
l1: printf("3 ");
}

A. Complie error

B. 3

C. 1

D. 1 3

#include <conio.h>
#include <stdio.h>
int main()
{
    int i = 0, j = 0;
    while (i < 2)
    {
l1: i++;
        while (j < 3)
        {
            printf("loop\n");
            goto l1;
        }
    }
    getch();
}

A. loop loop loop

B. Infinite loop

C. Complie error

void main()
{
    int a = 15, b = 10, c = 5;
    if(a > b > c)
        printf("True");
    else
        printf("False"); 
    getch();
}

A. True

B. False

C. Complier Error

D. Run time error

#include <stdio.h>
#include <conio.h>
void main()
{
    int i = 0;
    switch (i)
    {
    case '0': printf("A");
        break;
    case '1': printf("B");
        break;
    default: printf("ABC");
    }
    getch();
}

A. A

B. B

C. ABC

#include <stdio.h>
#include "conio.h"
void main()
{
    int i = 3;
    switch (i)
    {
    case 0+1: printf("A");
        break;
    case 1+2: printf("B");
        break;
    default: printf("ABC");
    }
    getch();
}

A. A

B. B

C. ABC

#include <stdio.h>
#include <conio.h>
#define A 0
#define B 1
int main()
{
    int i = 3;
    switch (i & 1)
    {
    case A: printf("FALSE");
        break;
    case B: printf("TRUE");
        break;
    default: printf("Default");
    }
    getch();
}

A. FALSE

B. TRUE

C.  Default

#include <stdio.h>
#include <conio.h>
int main()
{
    int i;
    if (printf("0"))
        i = 3;
    else
        i = 5;
    printf("%d", i);
    getch();
}

A. 3

B. 5

C. 03

D. 05

#include<stdio.h>
#include <conio.h>
int main()
{
    int a = 5;
    switch(a)
    {
    default:
        a = 4;
    case 6:
        a--;
    case 5:
        a = a + 1;
    case 1:
        a = a - 1;
    }
    printf("%d \n", a);
    getch();
}

A. 3

B. 4

C. 5

D. 6

#include <stdio.h>
#include <conio.h>
int main()
{
    int x = 3;
    if (x == 2); x = 0;
    if (x == 3) x++;
    else x += 2;
 
    printf("x = %d", x);
    getch();
}

A. x = 2

B.  x = 6

C. x = 0

#include <stdio.h>
#include <conio.h>
int main()
{
    int check = 20, arr[] = {10, 20, 30};
    switch (check)
    {
    case arr[0]: printf("A ");
    case arr[1]: printf("B");
    case arr[2]: printf("C");
    }
    getch();
}

A. ABC

B. BC

C. B

D. Complier Error

void main() 
{
    if ((1 || 0) && (0 || 1)) 
    {
        printf("ABC");
    } 
    else
    {
        printf("DEF");
    }
    getch();
}

A. ABC

B. DEF

C. Syntax error

#include <stdio.h>
#include <conio.h>
#include <string.h>
 
void main()
{
    char str1[] = "vncoding";
    char str2[] = "vncoding";
    if (strcmp(str1, str2))
        printf("Equal");
    else
        printf("Unequal");
 
    getch();
}

A. Equal

B. Unequal

C. nothing is printed

#include <stdio.h>
#include <conio.h>
 
void main()
{
    int i;
    i = 10;
    if(i == 20 || 30)
        printf("True");
    else
        printf("False");
 
    getch();
}

A. True

B. False

C. Complier error

#include <stdio.h>
#include <conio.h>
 
void main()
{
    if(1,0)
        printf("True");
    else
        printf("False");
 
    getch();
}

A. True 

B. False

C. Complier error

#include <stdio.h>
#include <conio.h>
 
void main()
{
    int i, j, *ptr, *ptr1;
    i = 10;
    j = 10;
    ptr = &i;
    ptr1 = &j;
 
    if(ptr == ptr1)
        printf("True");
    else
        printf("False");
 
    getch();
}

A. True

B. False

C. Complier error

#include <stdio.h>
#include <conio.h>
 
void main()
{
    int i;
    i = 2;
DES:
    printf("%d", i);
    i = i + 2;
    if(i <= 20)
        goto DES;
 

A. 2468101214161820

B. 468101214161820

C. nothing is printed

#include <stdio.h>
#include <conio.h>
 
void main()
{
    int i;
    i = 0;
    if(i = 15, 10, 5)
        printf("C/C++ %d", i);
    else
        printf("Java %d", i);
 
    getch();
}

A. C/C++ 15

B. Java 15

C. Java 5

D. Complier error

#include <stdio.h>
#include <conio.h>
 
void main()
{
    int a = 80;
    if(a++ > 80)
        printf("C/C++ %d", a);
    else
        printf("Java %d", a);
 
    getch();
}

A. C/C++ 80

B.  C/C++ 81

C.  Java 80

D. Java 81

#include <stdio.h>
#include <conio.h>
 
void main()
{
    int a;
    a = 1;
    while(a <= 1)
        if(a%2)
            printf("%d ", a++);
        else
            printf("%d ", ++a);
    printf("%d ", a+10);
 
    getch();
}

A. 1 12

B. 2 12

C. 2 11

#include <stdio.h>
#include <conio.h>
#include <string.h>
#include <stdlib.h>
 
void myfunc(char** param)
{
    ++param;
}
void main()
{
    char* string = (char*)malloc(64);
    strcpy(string, "hello_World");
    myfunc(&string);
    myfunc(&string);
    printf("%s\n", string);
    getch();
}

A. hello_World

B. ello_World

C. llo_World

D. lo_World

void myfunc(char** param)
{
    ++*param;
}
void main()
{
    char* string = (char*)malloc(64);
    strcpy(string, "hello_World");
    myfunc(&string);
    myfunc(&string);
    printf("%s\n", string);
    getch();
}

A. hello_World

B. ello_World

C. llo_World

D. lo_World

void main()
{
    int ints[] = { 0, 1, 2, 3 };
    int* i1 = ints + 1;
    int a = ++*i1;
    int b = a + *i1;
    printf("%d\n", b);
    getch();
}

A. 3

B. 4

C. 5

D. 6

void main()
{
    int ints[] = { 0, 5, 10, 15 };
    int* i2 = ints + 2;
    int a = *i2++; // a = *(i2++);
    printf("%d#%d\n", a, *i2);
    getch();
}

A. 10#15

B. 10#10

C. 15#15

D. 11#15

void main()
{
    int ints[] = { 0, 1, 2, 3 };
    int* i1 = ints + 1;
    int* i2 = ints + 2;
    int a = ++*i1 + *i2++;
    int b = *++i1 + *i2--;
    printf("%d#%d", a, b);
    getch();
}

A. 4#4

B. 4#5

C. 5#6

D. 4#6

void main()
{
    int i = 400;
    int *ptr = &i;
    *++ptr = 2;
    printf("%d %d", i, *ptr);
    getch();
}

A. 400 2

B. 400 400

C. 400 401

D. Complier error

void main()
{
    char str[] = {"pvpit"};
    char *s1 = str;
    s1++;
    printf("%c", *s1);
    getch();
}

A. pvpit

B. vpit

C. v

D. Another

void main()
{
    char *s = "\12345s\n";
    printf("%d", strlen(s));
    printf("\n%s", s);
    getch();
}

A. 5

B. 7

C. 9

D. 10

int main(int argc, char** argv)
{
    const char* foo = "wow"; // line 1
    foo = "top"; // line 2
    foo[0] = 1; // line 3
    return 0;
}

A. 1

B. 2

C. 3

D. None of the lines

void main() 
{ 
    int x = 5,y = 6;
    int* const p = &x;
    p = &y; 
    printf("%d", (*p)); 
    getch();
}

A. Complier error

B. 6

C. 5

D. Another

void main() 
{ 
    int x = 5, y = 8;
    const int* p;
    p = &x;
    p = &y;
    x++;
    printf("%d", *p); 
    getch();
}

A. 5

B. 6

C. 8

D. Complier Error

void main() 
{ 
    int x = 5;
    const int* p;
    p = &x;
    x++;
    *p = 4;
    printf("%d", *p); 
    getch();
}

A. 4

B. 5

C. 6

D. Complier Error

#include <stdio.h>
 
int main()
{
    int a = 320;
    char *ptr;
    ptr = (char*)&a;
    printf("%d ", *ptr);
    return 0;
}

A. 320

B. 64

C. Complier Error

#include <stdio.h>
 
int main()
{
    int i = 3;
    int *j;
    int **k;
    j = &i;
    k = &j;
    printf("%u , %u , %d ", k, *k, **k);
    return 0;
}

A. Address of j , Address of  i , 3

B. Complier Error

C. 3 , 3 , 3

#include <stdio.h>
#include <conio.h>
#include <string.h>
 
int main()
{
    char *ptr1 = NULL;
    char *ptr2 = 0;
    printf("\n%d", ptr2);
    strcpy(ptr1, "c");
    strcpy(ptr2, "questions");
    printf("\n%s %s", ptr1, ptr2);
    getch();
}

A.  printf("\n%d", ptr2);

B. strcpy(ptr1, "c");

C. strcpy(ptr2, "questions");

D. printf("\n%s %s", ptr1, ptr2);

#include <stdio.h>
#include <conio.h>
 
int main()
{
    int a = 10;
    void *p = &a;
    int *ptr = p;
    printf("%u\n", *ptr);
    getch();
}

A.  int a = 10;

B. void *p = &a;

C. int *ptr = p;

D. printf("%u\n", *ptr);

#include <stdio.h>
#include <conio.h>
 
int main()
{
    int a = 5, b = 10, c;
    int *p = &a, *q = &b;
    c = p - q;
    printf("%d" , c);
    getch();
}

A. 3

B. 4

C. 5

D. 6

#include <stdio.h>
#include <conio.h>
 
int main()
{
    int i = 5, j;
    int *p , *q;
    p = &i;
    q = &j;
    j = 5;
    printf("%d %d", *p, *q);
    getch();
}

A.  5 5

B. Complier Error

C. 5 Garbage value

#include <stdio.h>
#include <conio.h>
 
void main()
{
    int i = 5;
    int *p;
    p = &i;
    printf(" %u %u", *&p , &*p);
    getch();
}

A. Address of i Address of i

B. Garbage value Garbage value

C. Complier Error

#include <stdio.h>
#include <conio.h>
int main()
{
    int array[2][2][3]={0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
    printf("%d", array[1][0][2]);
    getch();
}

A. 6

B. 7

C. 8

D. 9

#include <stdio.h>
#include <conio.h>
void main()
{
    char arr[8]={'V','I','E','T','N','A','M'}; 
    char *p; 
    p=(char *)(arr+2)[2]; 
    printf("%c", p);  
    getch();
}

A. I

B. E

C. M

D. N

#include <stdio.h>
#include <conio.h>
void main()
{
    char ch[]={'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};
    int *p = (int*)ch;
    p++;
    printf("%x", *p);
    getch();
}

A. 37363534

B. 34353637

C. 45673333

#include <stdio.h>
#include <conio.h>
 
int main()
{
    int i = 11;
    int const * p = &i;
    p++;
    printf("%d", *p); 
    getch();
}

A. 11

B. 12

C. Garbage value

D. Complier error

A. 1,4

B. 3

C. 1,2

D. 1

A. strnstr()

B. strrchr()

C. laststr()

D. strstr()

#include <stdio.h>
#include  <conio.h>
int main()
{
    int a[3][4] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 };
    printf("%u, %u, %u\n", a[0]+1, *(a[0]+1), *(*(a+0)+1));
    getch();
}

A. 1006, 2, 2

B. 1006, 4, 4

C. 1002, 5, 5

D. Error

int (*ptr)[10];

A. ptr is array of pointers to 10 integers

B. ptr is a pointer to an array of 10 integers

C. ptr is an array of 10 integers

D. ptr is an pointer to array

#include <stdio.h>
#include <conio.h>
int main()
{
    char str[] = "LAPTRINHC++\0\.NET\0";
    printf("%s\n", str);
    getch();
}

A. LAPTRINHC++

B. LAPTRINHC++\0\.NET\0

C. LAPTRINHC++\0\.NET

#include <stdio.h>
#include <conio.h>
void swap(char *, char *);
 
int main()
{
    char *pstr[2] = {"LAPTRINHC++", ".NET"};
    swap(pstr[0], pstr[1]);
    printf("%s%s", pstr[0], pstr[1]);
    getch();
}
void swap(char *t1, char *t2)
{
    char *t;
    t=t1;
    t1=t2;
    t2=t;
}

A. LAPTRINHC++.NET

B.  .NETLAPTRINHC++

C.  Address of pstr[0] Address of pstr[1]