c - 我正在尝试使用 strcmp() 对 C 中的字符串数组进行排序

Question

我有一个令我头疼的家庭作业挑战。问题是:

Build a program that uses an array of strings to store the following names:
* "Florida"
* "Oregon"
* "California"
* "Georgia"
Using the preceding array of strings, write your own sort() function to display > each state's name in alphabetical order using the strcmp() function.

这是给我带来问题的代码:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

//function prototype
int sort(char *, char *);

int main() 
{
    char *strStates[] = {"Florida", "Oregon", "California", "Georgia"};
    char *strSorted[] = {0};
    int x;

    printf("\nThe list of states before being sorted in alphabetical order: ");

    for (x = 0; x < 4; x++) 
    {
        printf("\n%s", strStates[x]);
    }

    sort(strStates[x], strSorted[x]);

    printf("\nThe list of states sorted alphabetically are: ");

    for (x = 0; x < 4; x++) 
    {
        printf("\n%s", strStates[x]);
    }

    return 0;

}//end main

//function definition
int sort(char *string1, char *string2)
{
    int x;
    int y;

    for (x = 0; x < 3; x++) 
    {
        for (y = 1; y < 4; y++) 
        {
            if ((strcmp(string1[x], string1[y])) > 0) 
            {
                strcpy(string2, string1[x]);
                strcpy(string1[x], string1[y]);
                strcpy(string[y], string2);
            }//end if

       }//end inner for loop

    }//end outer for loop

}//end sort()

我在编译时遇到了一系列错误:

Chapter_8_Challenge_3.c:45:16: warning: incompatible integer to pointer conversion passing 'char' to parameter of type 'const char *'; take the address with & [-Wint-conversion]
                    if ((strcmp(string1[x], string1[y])) > 0) 
                                ^~~~~~~~~~
                                &  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/string.h:77:25: note: passing argument to parameter here
int      strcmp(const char *, const char *);
                        ^  
Chapter_8_Challenge_3.c:45:28: warning: incompatible integer to pointer conversion passing 'char' to parameter of type 'const char *'; take the address with & [-Wint-conversion]
                    if ((strcmp(string1[x], string1[y])) > 0) 
                                            ^~~~~~~~~~
                                            &  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/string.h:77:39: note: passing argument to parameter here
int      strcmp(const char *, const char *);
                                      ^  
Chapter_8_Challenge_3.c:47:21: warning: incompatible integer to pointer conversion passing 'char' to parameter of type 'const char *'; take the address with & [-Wint-conversion]
                            strcpy(string2, string1[x]);
                                            ^~~~~~~~~~
                                            &  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/secure/_string.h:83:33: note: expanded from macro 'strcpy'
  __builtin___strcpy_chk (dest, src, __darwin_obsz (dest))
                            ^  
Chapter_8_Challenge_3.c:48:12: warning: incompatible integer to pointer conversion passing 'char' to parameter of type 'const void *' [-Wint-conversion]
                            strcpy(string1[x], string1[y]);
                                   ^~~~~~~~~~  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/secure/_string.h:83:53: note: expanded from macro 'strcpy'
  __builtin___strcpy_chk (dest, src, __darwin_obsz (dest))
                                                ^  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/secure/_common.h:39:54: note: expanded from macro '__darwin_obsz'
#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)
                                                 ^  
Chapter_8_Challenge_3.c:48:12: warning: incompatible integer to pointer conversion passing 'char' to parameter of type 'char *'; take the address with & [-Wint-conversion]
                            strcpy(string1[x], string1[y]);
                                   ^~~~~~~~~~
                                   &  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/secure/_string.h:83:27: note: expanded from macro 'strcpy'
  __builtin___strcpy_chk (dest, src, __darwin_obsz (dest))
                      ^  
Chapter_8_Challenge_3.c:48:24: warning: incompatible integer to pointer conversion passing 'char' to parameter of type 'const char *'; take the address with & [-Wint-conversion]
                            strcpy(string1[x], string1[y]);
                                               ^~~~~~~~~~
                                               &  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/secure/_string.h:83:33: note: expanded from macro 'strcpy'
  __builtin___strcpy_chk (dest, src, __darwin_obsz (dest))
                            ^  
Chapter_8_Challenge_3.c:49:12: error: use of undeclared identifier 'string'; did you mean 'string1'?
                            strcpy(string[y], string2);
                                   ^~~~~~
                                   string1  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/secure/_string.h:83:27: note: expanded from macro 'strcpy'
  __builtin___strcpy_chk (dest, src, __darwin_obsz (dest))
                      ^  
Chapter_8_Challenge_3.c:36:16: note: 'string1' declared here
int sort(char *string1, char *string2)
           ^  
Chapter_8_Challenge_3.c:49:12: error: use of undeclared identifier 'string'
                            strcpy(string[y], string2);
                                   ^  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/secure/_string.h:83:53: note: expanded from macro 'strcpy'
  __builtin___strcpy_chk (dest, src, __darwin_obsz (dest))
                                                ^  
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/secure/_common.h:39:54: note: expanded from macro '__darwin_obsz'
#define __darwin_obsz(object) __builtin_object_size (object, _USE_FORTIFY_LEVEL > 1 ? 1 : 0)  
                                                 ^
6 warnings and 2 errors generated.

Answer 1

1. 在您的函数中排序 -

if((strcmp(string1[x],string1[y]))>0) //string1[x] is of type char-Wrong argument to strcmp 
        {
            strcpy(string2, string1[x]);          // same problem as aboce for all 
            strcpy(string1[x], string1[y]);
            strcpy(string[y], string2);
        }//end if 

此 string1 已经是 char * ，并且 string1[x] 将是 char 类型。所以这会调用未定义的行为。

2. 在 main 中 -

 for (x = 0; x < 4; x++) 
{
    printf("\n%s", strStates[x]);
}

sort(strStates[x], strSorted[x]);

也许您打算将 char 指针数组 (strStates) 传递给函数作为第一个参数，将 (strSorted) 作为第二个参数传递。那么上面sort中的问题也将得到解决。

3.最后你的函数int sort()不会返回任何东西，所以你又得到了自己UB.

注意 - 您收到的错误是由于将 char 传递给字符串函数所致。