C++ - 在字符和文本之间获取文本字符串

Question

我正在制作一个控制台程序，它将获取一行以特定字符开头的文本。我正在使用 .txt 文件作为文本输入，就是这样:

<?xml version="1.0" encoding="utf-8"?>
<vector android:height="64.0dip" android:width="64.0dip" android:viewportWidth="24.0" android:viewportHeight="24.0"
  xmlns:android="http://schemas.android.com/apk/res/android">
    <path android:fillColor="#00000000" android:pathData="M12.05,7.7c-1.1,0,-2,0.94,-2,2.05v0.5h4v-0.5C14.05,8.65,13.15,7.7,12.05,7.7z" />
    <path android:fillColor="@*common:color/qs_toggles_color" android:pathData="M15.05,10.25l0.0,-0.5c0.0,-1.66 -1.34,-3.0 -3.0,-3.0s-2.99,1.34 -2.99,3.0l-0.01,0.5c-0.55,0.0 -1.0,0.45 -1.0,1.0l0.0,5.0c0.0,0.55 0.45,1.0 1.0,1.0l6.0,0.0c0.55,0.0 1.0,-0.45 1.0,-1.0l0.0,-5.0C16.05,10.7 15.6,10.25 15.05,10.25zM12.05,14.75c-0.55,0.0 -1.0,-0.45 -1.0,-1.0c0.0,-0.55 0.45,-1.0 1.0,-1.0s1.0,0.45 1.0,1.0C13.05,14.3 12.6,14.75 12.05,14.75zM14.05,10.25l-4.0,0.0l0.0,-0.5c0.0,-1.1 0.9,-2.05 2.0,-2.05s2.0,0.94 2.0,2.05L14.05,10.25z" />
    <path android:fillColor="@*common:color/qs_toggles_color" android:pathData="M16.5,2.5c3.3,1.5 5.6,4.7 6.0,8.5L24.0,11.0C23.4,4.8 18.3,0.0 12.0,0.0c-0.2,0.0 -0.4,0.0 -0.7,0.0l3.8,3.8L16.5,2.5zM7.5,21.5c-3.3,-1.5 -5.6,-4.7 -6.0,-8.5L0.1,13.0C0.6,19.2 5.7,24.0 12.0,24.0c0.2,0.0 0.4,0.0 0.7,0.0l-3.8,-3.8L7.5,21.5z" />
</vector>

我想做的是提取

M12.05,7.7c-1.1,0,-2,0.94,-2,2.05v0.5h4v-0.5C14.05,8.65,13.15,7.7,12.05,7.7z

和:

M15.05,10.25l0.0,-0.5c0.0,-1.66 -1.34,-3.0 -3.0,-3.0s-2.99,1.34 -2.99,3.0l-0.01,0.5c-0.55,0.0 -1.0,0.45 -1.0,1.0l0.0,5.0c0.0,0.55 0.45,1.0 1.0,1.0l6.0,0.0c0.55,0.0 1.0,-0.45 1.0,-1.0l0.0,-5.0C16.05,10.7 15.6,10.25 15.05,10.25zM12.05,14.75c-0.55,0.0 -1.0,-0.45 -1.0,-1.0c0.0,-0.55 0.45,-1.0 1.0,-1.0s1.0,0.45 1.0,1.0C13.05,14.3 12.6,14.75 12.05,14.75zM14.05,10.25l-4.0,0.0l0.0,-0.5c0.0,-1.1 0.9,-2.05 2.0,-2.05s2.0,0.94 2.0,2.05L14.05,10.25z

和:

M16.5,2.5c3.3,1.5 5.6,4.7 6.0,8.5L24.0,11.0C23.4,4.8 18.3,0.0 12.0,0.0c-0.2,0.0 -0.4,0.0 -0.7,0.0l3.8,3.8L16.5,2.5zM7.5,21.5c-3.3,-1.5 -5.6,-4.7 -6.0,-8.5L0.1,13.0C0.6,19.2 5.7,24.0 12.0,24.0c0.2,0.0 0.4,0.0 0.7,0.0l-3.8,-3.8L7.5,21.5z

并将它们放入自己的字符串中。我试图通过删除这些字符串之前和之后的所有文本来做到这一点，但是我得到了一个未处理的异常，代码如下:

int main(int argc, const char * argv[])
{
    string str = "<?xml versim on=\"1.0\" encoding=\"utf-8\"?> <vector android:height=\"64.0dip\" android:width=\"64.0dip\" android:viewportWidth=\"24.0\" android:viewportHeight=\"24.0\" xmlns:android=\"http://schemas.android.com/apk/res/android\"> <path android:fillColor=\"#00000000\" android:pathData=\"M12.05,7.7c-1.1,0,-2,0.94,-2,2.05v0.5h4v-0.5C14.05,8.65,13.15,7.7,12.05,7.7z\" /> <path android:fillColor=\"@*common:color/qs_toggles_color\" android:pathData=\"M15.05,10.25l0.0,-0.5c0.0,-1.66 -1.34,-3.0 -3.0,-3.0s-2.99,1.34 -2.99,3.0l-0.01,0.5c-0.55,0.0 -1.0,0.45 -1.0,1.0l0.0,5.0c0.0,0.55 0.45,1.0 1.0,1.0l6.0,0.0c0.55,0.0 1.0,-0.45 1.0,-1.0l0.0,-5.0C16.05,10.7 15.6,10.25 15.05,10.25zM12.05,14.75c-0.55,0.0 -1.0,-0.45 -1.0,-1.0c0.0,-0.55 0.45,-1.0 1.0,-1.0s1.0,0.45 1.0,1.0C13.05,14.3 12.6,14.75 12.05,14.75zM14.05,10.25l-4.0,0.0l0.0,-0.5c0.0,-1.1 0.9,-2.05 2.0,-2.05s2.0,0.94 2.0,2.05L14.05,10.25z\" <path android:fillColor=\"@*common:color/qs_toggles_color\" android:pathData=\"M16.5,2.5c3.3,1.5 5.6,4.7 6.0,8.5L24.0,11.0C23.4,4.8 18.3,0.0 12.0,0.0c-0.2,0.0 -0.4,0.0 -0.7,0.0l3.8,3.8L16.5,2.5zM7.5,21.5c-3.3,-1.5 -5.6,-4.7 -6.0,-8.5L0.1,13.0C0.6,19.2 5.7,24.0 12.0,24.0c0.2,0.0 0.4,0.0 0.7,0.0l-3.8,-3.8L7.5,21.5z\" /> </vector>";
    string dp1= str;
    dp1.replace(dp1.find("<?xml version=\"1.0\" encoding=\"utf-8\"?> <vector android:height=\"64.0dip\" android:width=\"64.0dip\" android:viewportWidth=\"24.0\" android:viewportHeight=\"24.0\" xmlns:android=\"http://schemas.android.com/apk/res/android\"> <path android:fillColor=\"#00000000\" android:pathData=\""), 269, "");
    dp1.replace(dp1.find("/> <path android:fillColor=\"@*common:color/qs_toggles_color\" android:pathData=\"M15.05,10.25l0.0,-0.5c0.0,-1.66 -1.34,-3.0 -3.0,-3.0s-2.99,1.34 -2.99,3.0l-0.01,0.5c-0.55,0.0 -1.0,0.45 -1.0,1.0l0.0,5.0c0.0,0.55 0.45,1.0 1.0,1.0l6.0,0.0c0.55,0.0 1.0,-0.45 1.0,-1.0l0.0,-5.0C16.05,10.7 15.6,10.25 15.05,10.25zM12.05,14.75c-0.55,0.0 -1.0,-0.45 -1.0,-1.0c0.0,-0.55 0.45,-1.0 1.0,-1.0s1.0,0.45 1.0,1.0C13.05,14.3 12.6,14.75 12.05,14.75zM14.05,10.25l-4.0,0.0l0.0,-0.5c0.0,-1.1 0.9,-2.05 2.0,-2.05s2.0,0.94 2.0,2.05L14.05,10.25z/> <path android:fillColor=\"@*common:color/qs_toggles_color\" android:pathData=\"M15.05,10.25l0.0,-0.5c0.0,-1.66 -1.34,-3.0 -3.0,-3.0s-2.99,1.34 -2.99,3.0l-0.01,0.5c-0.55,0.0 -1.0,0.45 -1.0,1.0l0.0,5.0c0.0,0.55 0.45,1.0 1.0,1.0l6.0,0.0c0.55,0.0 1.0,-0.45 1.0,-1.0l0.0,-5.0C16.05,10.7 15.6,10.25 15.05,10.25zM12.05,14.75c-0.55,0.0 -1.0,-0.45 -1.0,-1.0c0.0,-0.55 0.45,-1.0 1.0,-1.0s1.0,0.45 1.0,1.0C13.05,14.3 12.6,14.75 12.05,14.75zM14.05,10.25l-4.0,0.0l0.0,-0.5c0.0,-1.1 0.9,-2.05 2.0,-2.05s2.0,0.94 2.0,2.05L14.05,10.25z\" <path android:fillColor=\"@*common:color/qs_toggles_color\" android:pathData=\"M16.5,2.5c3.3,1.5 5.6,4.7 6.0,8.5L24.0,11.0C23.4,4.8 18.3,0.0 12.0,0.0c-0.2,0.0 -0.4,0.0 -0.7,0.0l3.8,3.8L16.5,2.5zM7.5,21.5c-3.3,-1.5 -5.6,-4.7 -6.0,-8.5L0.1,13.0C0.6,19.2 5.7,24.0 12.0,24.0c0.2,0.0 0.4,0.0 0.7,0.0l-3.8,-3.8L7.5,21.5z\" /> </vector>\""), 525, "");

    std::cout << dp1 << endl;

    system ("PAUSE");
    return 0;
}

所以基本上，我想将上面提到的那 3 个字符串提取到它们自己的字符串中。我在想我可以根据它们的起始字符提取它们，也就是 M。谢谢

Answer 1

从 XML 文件中提取数据的一种好方法是使用 XML 解析器。如果您的 XML 文件发生更改，您将无法手动搜索要执行的字符串。

What XML parser should I use in C++?