Question

我正在尝试用c ++创建一个简单的疯狂libs程序，我想检查并查看用户输入的单词是否以元音开头，如果是，则更改单词前面的“a”，到一个“一个”。我已经能够存储第一个字符，但它不会与If语句中的其他字符进行比较。我这样做完全错了吗？

#include <string>
#include <iostream>
using namespace std;

int main() {
    string adj_3;
    string anN;
        char firstChar;

//      GETTING USER'S WORD 

        cout << "ADJECTIVE: " << endl;
        getline(cin, adj_3);

//      GETTING FIRST CHARACTER

        firstChar = adj_3[0];

//      SEEING IF IT'S A VOWEL (not working)

        if(firstChar == ('a' || 'e' || 'i' || 'o' || 'u' || 'A' || 'E' || 'I' || 'O' || 'U')) {
            anN = "n";
        }
        else {
            cout << "not working" << endl;
        }

    cout << "I am having a" << anN << " " << adj_3 << " time at camp." << endl;

}

Answer 1

||运算符需要应用于两个参数，如下所示：

if (firstChar == 'a' || firstChar == 'e' || firstChar == 'i' || ...)

firstChar == 'a'计算为布尔值。 firstChar == 'a' || firstChar == 'e'获取由这两个操作产生的两个布尔值，并返回另一个布尔值，然后将其作为第一个参数提供给下一个||操作。通过这种方式，您可以“链接”||操作，直到其中一个为真，或直到它们全部为假。

有关示例和说明，请参阅here。

Answer 2

hnefatl的答案是单向的。

你也可以使用没有break语句的switch case来检查元音。类似的东西：

switch(firstChar)
{
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
case 'A':
case 'E':
case 'I':
case 'O': 
case 'U': cout<<"Vowel";
}

除switch-case之外，if-else ladder优于<module name="ConstantName"> <property name="id" value="ConstantNameMain"/> <property name="severity" value="error"/> <property name="applyToPrivate" value="false"/> <property name="format" value="^[A-Z][A-Za-z0-9]*(_[A-Za-z0-9]+)*$"/> </module> <module name="ConstantName"> <property name="id" value="ConstantNameTest"/> <property name="severity" value="error"/> <property name="applyToPrivate" value="false"/> <property name="format" value="^[A-Z][A-Za-z0-9]*(_[A-Z0-9]+)*$"/> </module>，如https://stackoverflow.com/a/1028463/6594779所述。

Answer 3

逻辑运算符a==0 || b==1结合了两个布尔表达式，例如： true，如果两个操作数中的任何一个是'a'，则返回true。如果您将true之类的单个字符作为操作数传递，则会将其解释为'a'，因为97的值为97 != 0 => true和('a' || 'e' || 'i' || 'o' || 'u' || 'A' || 'E' || 'I' || 'O' || 'U')。因此，您的表达式true始终为firstchar == (....)，而firstchar == true与false相同，后者可能会if (firstChar == 'a' || firstChar == 'e' || firstChar == 'i' || ...)。

你可以写......

if (strchr(firstChar, "aeiouAEIOU") != NULL)) ...

...或

Build command failed.
Error while executing process /opt/android-sdk/cmake/3.6.4111459/bin/cmake with arguments {-H/home/max/Documents/AndroidStudioProjects/HelloJNI1/app/src/main/cpp -B/home/max/Documents/AndroidStudioProjects/HelloJNI1/app/.externalNativeBuild/cmake/arm8Release/arm64-v8a -GAndroid Gradle - Ninja -DANDROID_ABI=arm64-v8a -DANDROID_NDK=/opt/android-sdk/ndk-bundle -DCMAKE_LIBRARY_OUTPUT_DIRECTORY=/home/max/Documents/AndroidStudioProjects/HelloJNI1/app/build/intermediates/cmake/arm8/release/obj/arm64-v8a -DCMAKE_BUILD_TYPE=Release -DCMAKE_MAKE_PROGRAM=/opt/android-sdk/cmake/3.6.4111459/bin/ninja -DCMAKE_TOOLCHAIN_FILE=/opt/android-sdk/ndk-bundle/build/cmake/android.toolchain.cmake -DANDROID_PLATFORM=android-23 -DANDROID_TOOLCHAIN=clang}
-- Check for working C compiler: /opt/android-sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang
-- Check for working C compiler: /opt/android-sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang -- broken
-- Configuring incomplete, errors occurred!
See also "/home/max/Documents/AndroidStudioProjects/HelloJNI1/app/.externalNativeBuild/cmake/arm8Release/arm64-v8a/CMakeFiles/CMakeOutput.log".
See also "/home/max/Documents/AndroidStudioProjects/HelloJNI1/app/.externalNativeBuild/cmake/arm8Release/arm64-v8a/CMakeFiles/CMakeError.log".
CMake Error at /opt/android-sdk/cmake/3.6.4111459/share/cmake-3.6/Modules/CMakeTestCCompiler.cmake:61 (message):
  The C compiler
  "/opt/android-sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang"
  is not able to compile a simple test program.
  It fails with the following output:
   Change Dir: /home/max/Documents/AndroidStudioProjects/HelloJNI1/app/.externalNativeBuild/cmake/arm8Release/arm64-v8a/CMakeFiles/CMakeTmp
  Run Build Command:"/opt/android-sdk/cmake/3.6.4111459/bin/ninja"
  "cmTC_0053d"
  [1/2] Building C object CMakeFiles/cmTC_0053d.dir/testCCompiler.c.o
  FAILED:
  /opt/android-sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang
  --target=aarch64-none-linux-android
  --gcc-toolchain=/opt/android-sdk/ndk-bundle/toolchains/aarch64-linux-android-4.9/prebuilt/linux-x86_64
  --sysroot=/opt/android-sdk/ndk-bundle/sysroot -isystem
  /opt/android-sdk/ndk-bundle/sysroot/usr/include/aarch64-linux-android
  -D__ANDROID_API__=23 -g -DANDROID -ffunction-sections -funwind-tables
  -fstack-protector-strong -no-canonical-prefixes -Wa,--noexecstack -Wformat
  -Werror=format-security -fPIE -o
  CMakeFiles/cmTC_0053d.dir/testCCompiler.c.o -c
  /home/max/Documents/AndroidStudioProjects/HelloJNI1/app/.externalNativeBuild/cmake/arm8Release/arm64-v8a/CMakeFiles/CMakeTmp/testCCompiler.c
  /opt/android-sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-x86_64/bin/clang:
  error while loading shared libraries: libncurses.so.5: cannot open shared
  object file: No such file or directory
  ninja: build stopped: subcommand failed.
  CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
  CMakeLists.txt

Answer 4

您也可以使用数组，其中存储所有元音然后进行比较。如下所示：

   char vowels[10]={'a','e','i','o','u','A','E','I','O','U'};
   int flag=0;
   for(int i=0;i<10;i++)
   {
       if(vowels[i]==firstChar)
       {
           flag=1;
           anN="n";
       }
   }
   if(flag==1)
        cout << "I am having a" << anN << " " << adj_3 << " time at camp." << endl;
   else
       cout << "not working" << endl;

无法比较字符（c ++）

4 个答案: