该程序有问题，我不知道为什么????(我认为这是针对cmp的) [英] this program has a problem and i dont know why ????(i think it is for cmp)

问题描述

<pre lang="xml">// 2.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <conio.h>
#include <string>
#include <stdio.h>
#include <stdlib.h>

using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    char str[]="input";

    string p,s;
  char * pch;
  printf ("Splitting string \"%s\" into tokens:\n",str);
  pch = strtok (str," ,.-");
  int code;
  while (pch != NULL)
  {
    printf("%s\n",pch);
    pch = strtok (NULL, " ,.-");
    if(strcmp(pch,"input")){
        pch = strtok (NULL, " ,.-");
        s=pch;
        cout<<"enter:";
        cin>>s;
    }
  }

    getch();
    return 0;
}

:((<

:((

推荐答案

如果您要这样做的是:

If what you are trying to do is this:

switch(p) {
case "abcd":
 ...
case "pqr":
 ...
}

简短的答案是你做不到.要引用该标准，表达式必须是整数类型或存在明确转换为整数类型的类类型".字符串(或char *或char [])不是整数类型，不能明确地转换为一个.

如果愿意，请投票并接受.

彼得

the short answer is that you can''t do it. To quote the standard, "The expression must be of integral type or of a class type for which an unambiguous conversion to integral type exists." A string (or char * or char[]) is not an integral type and cannot be unambiguously converted to one.

If you like, vote and accept.

Peter

Peter_in_2780是正确的，不能那样做.您可以使用此:

Peter_in_2780 is right, it can''t be done like that. You could use this:

     if(!strcmp(p,"abcd")){
    ;
}
else if(!strcmp(p,"hello")){
    ;
}
else if(!strcmp(p,"world")){
    ;
}
else{
    ;
}

正如Thaddeus所建议的，您可以编写一个很大的if/else if行，或者在某些情况下，使用带回调的for循环会是一个更好的选择.

As Thaddeus suggested, you can write a huge if/else if line, or in some cases a for loop with callbacks would be a better choice.

typedef enum {
	SCN_ABCD, //"abcd"
	SCN_HELLO, //"hello"
	SCN_WORLD, //"world"
} StringChoiceNumbers;

typedef struct {
	StringChoiceNumbers eCase;
	LPCSTR szCase;
} StringChoice;

StringChoice scOptions[] = {
	{ SCN_ABCD, "abcd" },
	{ SCN_HELLO, "hello" },
	{ SCN_WORLD, "world" },
};

void ProcessStringOption(StringChoiceNumbers eOption) {
	switch (eOption) {
		case SCN_ABCD:
			//case "abcd"
			break;

		case SCN_HELLO:
			//case "hello"
			break;

		case SCN_WORLD:
			//case "world"
			break;
	}
}

//in some function that needs a switch(p) on strings
for (int i = 0; i < ARRAYSIZE(scOptions); ++i) {
	if (strcmp(scOptions[i].szCase, p) == 0) {
		ProcessStringOption(scOptions[i].eCase);
	}
}

从处理的角度来看，它速度较慢，但​​是可以提高代码的局部性.
如果您需要调用函数中的大量变量，则可能无法使用它.
也可以不使用任何enum位来完成此操作，而使用LPSTR数组而不是创建结构，只需为每个字符串分配一个纯整数就可以简化它.

From a processing point of view it is slower, however it improves code locality.
You may no be able to use this if you need a large number of variables from the calling function.
This can also be done without any of the enum bit and use an array of LPSTR instead of creating a structs, and just assign a plain integer to each string to simplify it a bit.

LPCSTR szOptions[] = {
	"abcd",
	"hello",
	"world",
};

void ProcessStringOption(DWORD nOption) {
	switch (nOption) {
		case 0:
			//case "abcd"
			break;

		case 1:
			//case "hello"
			break;

		case 2:
			//case "world"
			break;
	}
}

//in some function that needs a switch(p) on strings
for (int i = 0; i < ARRAYSIZE(szOptions); ++i) {
	if (strcmp(scOptions[i], p) == 0) {
		ProcessStringOption(i);
	}
}

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