如何用另一个字符串替换字符串的所有实例？ [英] How do I replace all instances of a string with another string?

问题描述

我在另一个堆栈问题上发现了这个问题：

I found this on another stack question:

//http://stackoverflow.com/questions/3418231/c-replace-part-of-a-string-with-another-string
//
void replaceAll(std::string& str, const std::string& from, const std::string& to) {
    size_t start_pos = 0;
    while((start_pos = str.find(from, start_pos)) != std::string::npos) {
        size_t end_pos = start_pos + from.length();
        str.replace(start_pos, end_pos, to);
        start_pos += to.length(); // In case 'to' contains 'from', like replacing 'x' with 'yx'
    }
}

和我的方法：

string convert_FANN_array_to_binary(string fann_array)
{
    string result = fann_array;
    cout << result << "\n";
    replaceAll(result, "-1 ", "0");
    cout << result << "\n";
    replaceAll(result, "1 ", "1");
    return result;
}

其中，对于此输入：

cout << convert_FANN_array_to_binary("1 1 -1 -1 1 1 ");

现在，输出应为110011

now, the output should be "110011"

这里是方法的输出：

1 1 -1 -1 1 1  // original
1 1 0 1  // replacing -1's with 0's
11 1  // result, as it was returned from convert_FANN_array_to_binary()

我一直在看replaceAll代码，我真的不知道为什么用一个0代替连续的-1，然后不返回任何0（和一些1）最后结果。 = \

I've been looking at the replaceAll code, and, I'm really not sure why it is replacing consecutive -1's with one 0, and then not returning any 0's (and some 1's) in the final result. =\

推荐答案

错误在 str.replace（start_pos，end_pos，to） / code>

The bug is in str.replace(start_pos, end_pos, to);

从std :: string doc http://www.cplusplus.com/reference/string/string/replace/

From the std::string doc at http://www.cplusplus.com/reference/string/string/replace/

string& replace ( size_t pos1, size_t n1,   const string& str );

您正在使用结束位置，而函数需要一个长度。

You are using an end-position, while the function expects a length.

因此改为：

while((start_pos = str.find(from, start_pos)) != std::string::npos) {
         str.replace(start_pos, from.length(), to);
         start_pos += to.length(); // ...
}

注意：未经测试。

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