C++ - 如何将一个字符附加到字符*？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/19891962/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
C++ - How to append a char to char*?
提问by sonlexqt
I've tried so may ways on the Internet to append a character to a char* but none of them seems to work. Here is one of my incomplete solution:
我已经尝试过在 Internet 上将字符附加到 char* 的方法，但它们似乎都不起作用。这是我不完整的解决方案之一：
char* appendCharToCharArray(char * array, char a)
{
char* ret = "";
if (array!="")
{
char * ret = new char[strlen(array) + 1 + 1]; // + 1 char + 1 for null;
strcpy(ret,array);
}
else
{
ret = new char[2];
strcpy(ret,array);
}
ret[strlen(array)] = a; // (1)
ret[strlen(array)+1] = 'char* appendCharToCharArray(char* array, char a)
{
size_t len = strlen(array);
char* ret = new char[len+2];
strcpy(ret, array);
ret[len] = a;
ret[len+1] = 'std::string str;
str.append('x');
// or
str += x;
';
return ret;
}
';
return ret;
}
This only works when the passed array is "" (blank inside). Otherwise it doesn't help (and got an error at (1)). Could you guys please help me with this ? Thanks so much in advanced !
这仅在传递的数组为“”（内部空白）时有效。否则它没有帮助（并且在（1）处出错）。你们能帮我解决这个问题吗？非常感谢先进！
回答by masoud
Remove those char * retdeclarations inside ifblocks which hide outer ret. Therefor you have memory leak and on the other hand un-allocated memory for ret.
删除隐藏外部的块char * ret内的那些声明。因此，您有内存泄漏，另一方面.ifretret
To compare a c-style string you should use strcmp(array,"")not array!="". Your final code should looks like below:
要比较 c 样式的字符串，您应该使用strcmp(array,"")not array!=""。您的最终代码应如下所示：
bool AppendCharToCharArray( char *array, size_t n, char c )
{
size_t sz = std::strlen( array );
if ( sz + 1 < n )
{
array[sz] = c;
array[sz + 1] = 'char * CharArrayPlusChar( const char *array, char c )
{
size_t sz = std::strlen( array );
char *s = new char[sz + 2];
std::strcpy( s, array );
s[sz] = c;
s[sz + 1] = 'char * ret = new char[strlen(array) + 1 + 1];
^^^^^^ Remove this
';
return ( s );
}
';
}
return ( sz + 1 < n );
}
Note that, you must handle the allocated memory of returned retsomewhere by delete[]it.
请注意，您必须处理它在ret某处返回的分配内存delete[]。
Why you don't use std::string? it has .appendmethod to append a character at the end of a string:
你为什么不使用std::string？它有.append在字符串末尾附加一个字符的方法：
if (array!="") // Wrong - compares pointer with address of string literal
if (array[0] == 0) // Better - checks for empty string
回答by Vlad from Moscow
The function name does not reflect the semantic of the function. In fact you do not append a character. You create a new character array that contains the original array plus the given character. So if you indeed need a function that appends a character to a character array I would write it the following way
函数名不反映函数的语义。实际上，您没有附加字符。您创建一个包含原始数组和给定字符的新字符数组。因此，如果您确实需要一个将字符附加到字符数组的函数，我会按以下方式编写它
std::string appendCharToString(std::string const & s, char a) {
return s + a;
}
If you need a function that will contain a copy of the original array plus the given character then it could look the following way
如果您需要一个包含原始数组副本和给定字符的函数，则它可能如下所示
char ch = 't';
char chArray[2];
sprintf(chArray, "%c", ch);
char chOutput[10]="tes";
strcat(chOutput, chArray);
cout<<chOutput;
回答by Mike Seymour
The specific problem is that you're declaring a new variable instead of assigning to an existing one:
具体问题是您要声明一个新变量而不是分配给现有变量：
test
and trying to compare string values by comparing pointers:
并尝试通过比较指针来比较字符串值：
##代码##although there's no need to make that comparison at all; the first branch will do the right thing whether or not the string is empty.
尽管根本没有必要进行这种比较；无论字符串是否为空，第一个分支都会做正确的事情。
The more general problem is that you're messing around with nasty, error-prone C-style string manipulation in C++. Use std::stringand it will manage all the memory allocation for you:
更普遍的问题是你在 C++ 中处理讨厌的、容易出错的 C 风格的字符串操作。使用std::string它将为您管理所有内存分配：
回答by Safa Seed
OUTPUT:
输出：
##代码##