C++ g++ 错误：'malloc' 未在此范围内声明
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g++ error: ‘malloc’ was not declared in this scope
提问by Ovilia
I'm using g++ under Fedora to compile an openGL project, which has the line:
我在 Fedora 下使用 g++ 来编译一个 openGL 项目，它有以下行：
textureImage = (GLubyte**)malloc(sizeof(GLubyte*)*RESOURCE_LENGTH);
When compiling, g++ error says:
编译时，g++错误说：
error: ‘malloc' was not declared in this scope
Adding #include <cstdlib>doesn't fix the error.
添加#include <cstdlib>不会修复错误。
My g++ version is: g++ (GCC) 4.4.5 20101112 (Red Hat 4.4.5-2)
我的 g++ 版本是： g++ (GCC) 4.4.5 20101112 (Red Hat 4.4.5-2)
回答by user786653
You should use newin C++ code rather than mallocso it becomes new GLubyte*[RESOURCE_LENGTH]instead. When you #include <cstdlib>it will load mallocinto namespace std, so refer to std::malloc(or #include <stdlib.h>instead).
你应该new在 C++ 代码中使用而不是malloc让它变成new GLubyte*[RESOURCE_LENGTH]。当您#include <cstdlib>将它加载malloc到 namespace 时std，请参考std::malloc（或#include <stdlib.h>改为）。
回答by dragonroot
You need an additional include. Add <stdlib.h>to your list of includes.
你需要一个额外的包含。添加<stdlib.h>到您的包含列表中。
回答by Eric Leschinski
Reproduce this error in g++ on Fedora:
在 Fedora 上的 g++ 中重现此错误：
How to reproduce this error as simply as possible:
如何尽可能简单地重现此错误：
Put this code in main.c:
将此代码放在 main.c 中：
#include <stdio.h>
int main(){
int *foo;
foo = (int *) std::malloc(sizeof(int));
*foo = 50;
printf("%d", *foo);
}
Compile it, it returns a compile time error:
编译它，它返回一个编译时错误：
el@apollo:~$ g++ -o s main.c
main.c: In function ‘int main()':
main.c:5:37: error: ‘malloc' was not declared in this scope
foo = (int *) malloc(sizeof(int));
^
Fix it like this:
像这样修复它：
#include <stdio.h>
#include <cstdlib>
int main(){
int *foo;
foo = (int *) std::malloc(sizeof(int));
*foo = 50;
printf("%d", *foo);
free(foo);
}
Then it compiles and runs correctly:
然后它编译并正确运行：
el@apollo:~$ g++ -o s main.c
el@apollo:~$ ./s
50
