C questions

int *pi;
char *pc;
short int *psi;
printf(“ %d n”,sizeof(pi));
printf(“ %d n”,sizeof(pc));
printf(“ %d n”,sizeof(psi));
int *pi;
char *pc;
short int *psi;
printf(“ %d n”,sizeof(*pi));
printf(“ %d n”,sizeof(*pc));
printf(“ %d n”,sizeof(*psi));

int *pi = (int *)2000;
char *pc = (char *)2000;
pi++;
pc++;
printf(“ %u %u “ , pi , pc);

int x = 0x1234;
char c = x;
printf(“ %x “ , c);

const int x = 10;
1.int * const ptr1 = &x;
2.int const * ptr2 = &x;
3.const int * ptr3 = &x;

void update(int *p)
{
*p = *p + 5;
}
int main( )
{
int x = 10;
int *ptr = &x;
update(ptr);
printf(“x = %d “ , x);
}

void update(int *p)
{
p = p + 1;
}
int main( )
{
int arr[ ] = {10 , 12 , 25 , 45};
int *ptr = arr;
update(ptr);
printf(“*ptr = %d “ , *ptr);
}

void update(int *p)
{
*p = *p + 1;
}
int main( )
{
int arr[ ] = {10 , 12 , 25 , 45};
int *ptr = arr;
update(ptr);
printf(“*ptr = %d “ , *ptr);
}

void update(char *str)
{
str = “Devendra”;
}
int main( )
{
char *name = “Nimisha”;
update(name);
printf(“ %s n” , name);
}

{
str[0] = ‘H’;
}
int main( )
{
char name[ ] = “Nimisha”;
char *ptr = name;
update(ptr);
}

{
*++str = ‘a’;
}
int main( )
{
char name[ ] = “Nimisha”;
char *ptr = name;
update(ptr);
}

int main( )
{
char names[]
[10]={“OBAMA”,”PUTIN”,”MODI”,”CAMEROON”};
printf(“ %__ “ , *(names + 2) + 3);
printf(“ %__ “ , **(names + 2) + 3);
}

int main( )
{
char names[][10]={“OBAMA”,”PUTIN”,”MODI”,”CAMEROON”};
1. printf(“ %s “ , *(++names));
2. printf(“ %s “ , ++*(names));
3. printf(“ %c “ , ++**(names));
}

int main( )
{
char *names[10]={“OBAMA”,”PUTIN”,”MODI”,”CAMEROON”};
1. printf(“ %s “ , *(++names));
2. printf(“ %s “ , ++*(names));
3. printf(“ %c “ , ++**(names));
}

struct Student
{
int id;
char name[20];
};
int main( )
{
struct Student s1 = {1 , “Ayushi”};
struct Student s2 = {2 , “Ayushi”};
if(s1.name == s2.name)
printf(“Equal”);
else
printf(“Not Equal”);
}

char *names[ ] = {“Nimisha”,”Devender”,”Vikram”,”Balwant”};
printf(“ %d “ , sizeof(names));
printf(“ %d “ , sizeof(names[0]));
char names[ ][10] = {“Nimisha”,”Devender”,”Vikram”,”Balwant”};
printf(“ %d “ , sizeof(names));
printf(“ %d “ , sizeof(names[0]));

void display( char *names[ ])
{
printf(“Display : %d n “ , sizeof(names));
}
int main( )
{
char *names[ ] = {“Nimisha”,”Devender”,”Vikram”,”Balwant”};
printf(“Main : %d n“ , sizeof(names));
display( names );
}

static int x = 5;
int main( )
{
int x;
printf(“x = %d n”,x);
}

static int x = 5;
int main( )
{
extern int x;
printf(“x = %d n”,x);
}

int a = 5;
int b;
static int c = 7;
static int d;
int main( )
{
}
• Mention the memory segments of
variables after compiling (.o file) and
after linking (a.out)
• What is the difference between a
and c.
• Use nm utility to view the memory
segments
$gcc –c file.c
$nm file.o
$gcc file.c
$nm ./a.out

void func( );
int x;
int main( )
{
x = 5;
func( );
}
int x;
void func( )
{
x = 10;
}

[sikander@localhost ~]$ gcc -c f1.c
[sikander@localhost ~]$ gcc -c f2.c
[sikander@localhost ~]$ nm f1.o
U func
00000000 T main
U printf
00000004 C x
[sikander@localhost ~]$ nm f2.o
00000000 T func
00000004 C x
[sikander@localhost ~]$ gcc f1.o f2.o
[sikander@localhost ~]$ nm a.out
080495ac B x

void func( );
int x = 5;
int main( )
{
func( );
}
int x = 10;
void func( )
{
x++;
}

 [sikander@localhost ~]$ gcc -c f1.c
 [sikander@localhost ~]$ gcc -c f2.c
 [sikander@localhost ~]$ nm f1.o
 00000000 D x
 00000000 D x
 [sikander@localhost ~]$ gcc f1.o f2.o
 f2.o(.data+0x0): multiple definition of `x'
 f1.o(.data+0x0): first defined here
 collect2: ld returned 1 exit status

C C
B
C D
D
D D
Multiple Definition
d d
No Conflict, two different variables
b b
d b
b d
b D

int x ; //C
int main( )
{
printf(“Main &x= %p” , &x);
printf(“x = %d n”, x);
func( );
}
int x ; //C
void func( )
{
printf(“Func &x= %p” , &x);
}
int x ; //C
int main( )
{
func( );
}
int x = 5 ; //D
void func( )
{
}

void func( );
int x = 5; //D
int main( )
{
func( );
}
int x = 10; //D
void func( )
{
}
void func( );
static int x = 5; //d
int main( )
{
func( );
}
int x = 10; //D
void func( )
{
}

const int x = 10; //Read Only
int main( )
{
const int y = 5; //Stack
}

const int x = 10; //Read Only
int main( )
{
const int y = 5; //Stack
printf(“Enter the value for local const variable : “);
scanf(“ %d”,&y);
printf(“Local Const = %d n” , y);
printf(“Enter the value for global const variable : “);
scanf(“ %d”,&x);
printf(“Global Const = %d n”,x);
}
[sikander@localhost ~]$ ./a.out
Enter the value for local const variable : 89
Local Const = 89
Enter the value for global const variable : 6
Segmentation fault

 00000000 t display
 0000000a T main
 00000005 T print
static void display()
{
}
void print()
{
}
int main( )
{
display( );
print( );
}

C questions

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