为字符串动态分配内存的一般方法 [英] General method for dynamically allocating memory for a string
问题描述
我在互联网上搜索了malloc和动态malloc;但是，我仍然不知道或者很容易看到什么是将内存分配给char的一般方法*
变量我想要分配我在里面找到的子字符串一个
字符串。
任何想法？
I have searched the internet for malloc and dynamic malloc; however, I still
don''t know or readily see what is general way to allocate memory to char *
variable that I want to assign the substring that I found inside of a
string.
Any ideas?
推荐答案
" smnoff" < 34 ************** @ hotmail.comwrites：
"smnoff" <34**************@hotmail.comwrites:
我在互联网上搜索了malloc和动态malloc;但是，我仍然不知道或者很容易看到什么是将内存分配给char的一般方法*
变量我想要分配我在里面找到的子字符串一个
字符串。
I have searched the internet for malloc and dynamic malloc; however, I still
don''t know or readily see what is general way to allocate memory to char *
variable that I want to assign the substring that I found inside of a
string.
如果要为字符串分配内存，请将
非空字符的数量加一，再加上malloc ，然后将
字符串复制到其中，确保空终止结果。
如果你可以更具体地说明你在尝试什么要做，
也许我们可以提供一些细节帮助。
-
我希望，有一天，学会阅读。
似乎比写作更难。
- 理查德希思菲尔德
If you want to allocate memory for a string, pass the number of
non-null characters in it, plus one, to malloc, then copy the
string into it, being sure to null-terminate the result.
If you can be more specific about what you''re trying to do,
perhaps we can help with some details.
--
"I hope, some day, to learn to read.
It seems to be even harder than writing."
--Richard Heathfield
smnoff发布：
smnoff posted:
我在互联网上搜索了malloc和动态malloc;但是，我还是不知道或者很容易看到什么是分配内存的一般方法
到char *变量我想要分配我找到的子字符串
在一个字符串里面。
有什么想法吗？
I have searched the internet for malloc and dynamic malloc; however, I
still don''t know or readily see what is general way to allocate memory
to char * variable that I want to assign the substring that I found
inside of a string.
Any ideas?
未经检查的代码，可能包含一两个错误：
#include< stdlib.h>
#include< stddef.h>
#include< assert.h>
char * to_release;
void ReleaseLastString（无效）
{
免费（to_release）;
}
char const * CreateSubstring（char const * const p，
size_t const istart，size_t const iend）
{
int assert_dummy =（断言（!! p），断言（!! istart），断言（!! iend），0）;
if（！p [iend + 1]）return to_release = 0，p + istart;
to_release = malloc（iend - istart + 1）;
memcpy（to_release，p，iend - istart）;
to_release [iend - istart] = 0;
return to_release;
}
int main（）
{
puts（CreateSubstring（" abcdefghijklmnop"，2,7））;
ReleaseLastString（）;
puts（CreateSubstring （abcdefghijklmnop，4,15））;
ReleaseLastString（）;
}
-
Frederick Gotham
Unchecked code, may contain an error or two:
#include <stdlib.h>
#include <stddef.h>
#include <assert.h>
char *to_release;
void ReleaseLastString(void)
{
free(to_release);
}
char const *CreateSubstring(char const *const p,
size_t const istart,size_t const iend)
{
int assert_dummy = (assert(!!p),assert(!!istart),assert(!!iend),0);
if(!p[iend+1]) return to_release = 0, p + istart;
to_release = malloc(iend - istart + 1);
memcpy(to_release,p,iend - istart);
to_release[iend - istart] = 0;
return to_release;
}
int main()
{
puts(CreateSubstring("abcdefghijklmnop",2,7));
ReleaseLastString();
puts(CreateSubstring("abcdefghijklmnop",4,15));
ReleaseLastString();
}
--
Frederick Gotham
" Frederick Gotham" < fg ******* @ SPAM.com在留言中写道
新闻：r9 ******************* @ news.indigo .ie ...
"Frederick Gotham" <fg*******@SPAM.comwrote in message
news:r9*******************@news.indigo.ie...
smnoff发布：
smnoff posted:
>我在互联网上搜索了malloc和动态malloc;但是，我仍然不知道或者很容易看到将内存分配给char *变量的一般方法是什么，我想在字符串中分配我找到的子字符串。
任何想法？
>I have searched the internet for malloc and dynamic malloc; however, I
still don''t know or readily see what is general way to allocate memory
to char * variable that I want to assign the substring that I found
inside of a string.
Any ideas?
未经检查的代码，可能包含一两个错误：
#include< stdlib.h>
#include< stddef.h>
#include< assert.h>
char * to_release;
void ReleaseLastString（无效）
{
免费（to_release）;
}
char const * CreateSubstring（char const * const p，
size_t const istart，size_t const iend）
{
int assert_dummy =（assert（!! p），assert（!! istart），assert（!! iend），0）;
Unchecked code, may contain an error or two:
#include <stdlib.h>
#include <stddef.h>
#include <assert.h>
char *to_release;
void ReleaseLastString(void)
{
free(to_release);
}
char const *CreateSubstring(char const *const p,
size_t const istart,size_t const iend)
{
int assert_dummy = (assert(!!p),assert(!!istart),assert(!!iend),0);
为什么上面的行显示有双重感叹号？
Why are there double exclamation marks in the line show above?
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