в 14:20, 25 мая 2010

2010-05-25T14:20:56Z

Admin: 1 версия: Импорт контента...

2010-05-25T10:22:35Z

1 версия: Импорт контента...

Новая страница

== Allocate array in memory: how to use calloc==

<source lang="cpp">

#include <stdio.h>
#include <stdlib.h>
int main ()
{
int i, n;
int *pointerData;
printf ("Enter number of items to be stored: ");
scanf ("%d", &i);
pointerData = (int*) calloc (i, sizeof(int));

if (pointerData==NULL)
exit (1);

for (n = 0; n < i; n++)
{
printf ("Enter number #%d: ", n);
scanf ("%d", &pointerData[ n ]);
}
printf ("You have entered: ");

for (n = 0; n < i; n++)
printf ("%d ", pointerData[ n ]);
free (pointerData);
return 0;
}

</source>

==Allocate memory==

<source lang="cpp">
#include <stdlib.h>
#include <stdio.h>
int main()
{
float *p;
p = calloc(100, sizeof(float));
if(!p) {
printf("Allocation Error\n");
exit(1);
}
return 0;
}

</source>

==Allocate memory and reallocate==

<source lang="cpp">
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int main(void)
{
char *p;
p = malloc(17);
if(!p) {
printf("Allocation Error\n");
exit(1);
}
strcpy(p, "This is 16 chars");
p = realloc(p, 18);
if(!p) {
printf("Allocation Error\n");
exit(1);
}
strcat(p, ".");
printf(p);
free(p);
return 0;
}

</source>

== Allocate memory block: how to use malloc==

<source lang="cpp">
#include <stdio.h>
#include <stdlib.h>
int main ()
{
int i, n;
char *str;
printf ("String Length? ");
scanf ("%d", &i);
str = (char*) malloc (i+1);
if (str == NULL)
exit (1);
for ( n = 0; n < i; n++)
str[n] = rand() % 26 + "a";

str[i] = "\0";
printf ("Random string: %s\n", str);
free (str);
return 0;
}

</source>

==Allocate space for a string dynamically, request user input, and then print the string backwards==

<source lang="cpp">

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int main(void)
{
char *s;
register int i;
s = malloc(80);
if(!s) {
printf("Memory request failed.\n");
exit(1);
}
gets(s);
for(i = strlen(s) - 1; i >= 0; i--)
putchar(s[ i ]);
free(s);
return 0;
}

</source>

==Find out the address after malloc==

<source lang="cpp">
#include <stdio.h>
#include <malloc.h>
main() {
int *base;
int i,j;
int cnt = 3;
int sum = 0;

base = (int *)malloc(cnt * sizeof(int));
printf("the base of allocation is %16lu \n",base);
if(!base)
printf("unable to allocate size \n");
else {
for(j = 0;j < cnt; j++)
*(base+j)=5;
}
for(j = 0;j < cnt; j++)
sum = sum + *(base+j);
printf("total sum is %d\n",sum);
free(base);
printf("the base of allocation is %16lu \n",base);
base = (int *)malloc(cnt * sizeof(int));
printf("the base of allocation is %16lu \n",base);
free(base);
base = (int *)calloc(10,2);
printf("the base of allocation is %16lu \n",base);
free(base);
}

</source>

==Get the current system free memory ==

<source lang="cpp">
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
char *p;
long l;
l = 0;
do {
p = malloc(1000);
if(p)
l += 1000;
} while(p);
printf("Approximately %ld bytes of free memory.", l);
return 0;
}

</source>

== Reallocate memory block: how to use realloc==

<source lang="cpp">
#include <stdio.h>
#include <stdlib.h>
int main ()
{
int input, n;
int count=0;
int *numbers = NULL;
do {
printf ("Enter an integer value ( enter 0 to stop): ");
scanf ("%d", &input);
count++;
numbers = (int*) realloc (numbers, count * sizeof(int));
if (numbers == NULL) {
puts ("Error (re)allocating memory");
exit ( 1 );
}
numbers[ count - 1 ] = input;
} while (input!=0);
printf ("Numbers entered: ");

for ( n = 0; n < count; n++)
printf ("%d ",numbers[ n ]);

free (numbers);
return 0;
}

</source>

==Store string in allocated memory==

<source lang="cpp">
#include <stdlib.h>
#include <stdio.h>
int main(void)
{
char *str[100];
int i;
for(i = 0; i < 100; i++) {
if((str[i] = malloc( 128 )) == NULL) {
printf("Allocation Error\n");
exit(1);
}
gets(str[i]);
}
/* now free the memory */

for(i = 0; i < 100; i++)
free(str[i]);
return 0;
}

</source>

==Use malloc to allocate memory==

<source lang="cpp">
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
char *p;
p = malloc(80);
if( !p ) {
printf("Memory Allocation Failed");
exit(1);
}
printf("Enter a string: ");
gets( p );

printf( p );
free( p );
return 0;
}

</source>

← Предыдущая	Версия 14:20, 25 мая 2010
(нет различий)

C/Memory/Memory Allocation - История изменений

в 14:20, 25 мая 2010

Admin: 1 версия: Импорт контента...