编译出错cstring问题

[han4235]

请问， 我用的编译器gcc 4.4.5-6
error: 'strlen' was not declared in this scope
总是出现这个问题， 我在网上查了下 说是要加#include <cstring>
但是加了之后就出现这个问题
from hash.cpp:2:
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:76: error: '::memchr' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:77: error: '::memcmp' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:78: error: '::memcpy' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:79: error: '::memmove' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:80: error: '::memset' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:81: error: '::strcat' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:82: error: '::strcmp' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:83: error: '::strcoll' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:84: error: '::strcpy' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:85: error: '::strcspn' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:86: error: '::strerror' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:87: error: '::strlen' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:88: error: '::strncat' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:89: error: '::strncmp' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:90: error: '::strncpy' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:91: error: '::strspn' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:92: error: '::strtok' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:93: error: '::strxfrm' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:94: error: '::strchr' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:95: error: '::strpbrk' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:96: error: '::strrchr' has not been declared
/usr/lib/gcc/x86_64-redhat-linux/4.4.5/../../../../include/c++/4.4.5/cstring:97: error: '::strstr' has not been declared

我是用的automake生成的工程代码， 如果写了一个测试文件
#include <cstring>

int main()
{

char *xx = "dsdf";
strlen(xx);
return 1;
}

这样编译又没问题
百思不得其解
请问这是什么问题啊？

[xiaoyaoxiaonizi]

你用g++编译吧，CString明显是C++头文件

[han4235]

是的， 我是用g++编译的

[ri_aje]

有可能是头文件包含顺序产生了不良影响，把 hash.cpp 的代码上全或者试着调整 #include <cstring> 的包含位置，看看问题会不会消失。

[han4235]

#ifndef HASH_H #define HASH_H #include <cstring> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <malloc.h> #include <assert.h> #include <math.h> using namespace std;

[ri_aje]

把 #include <cstring> 放在所有 include 最后面试一下，或者索性你就 #include <string.h> 吧。

[han4235]

不行啊， 我放到最后也一样是这个错误， 换成string.h 干脆 hash.cpp: In function 'unsigned int hash4(const void*, unsigned int)': hash.cpp:39: error: 'strlen' was not declared in this scope 直接找不到strlen了

[qq_16135483]

我也遇到了这个问题，敢问LZ解决了吗？方便传授下经验吗？

[fefe82]

把预编译的结果打出来排查一下原因。 gcc / g++ 可以在命令行上加 -E -dD 输出预编译结果。

[赵4老师]

偶遇到类似问题都是用 “每次用/*...*/注释掉不同部分再重新编译，直到定位到具体语法出错的位置。” 的方法解决的。