我正在尝试将我编写的Java代码转换为C，我刚开始学习C并且我将它与Java混淆。
我的java代码：
public class Biggest
{
private static int testsExecuted = 0;
private static int testsFailed = 0;
public static void main(String[] args)
{
System.out.println("Testing typical cases, including punctuation\n");
testLongestWord("the quick brown foxes jumped over the lazy dogs", "jumped");
testLongestWord("hello world she said", "hello");
testLongestWord("Hello\tworld\tshe\tsaid", "Hello");
testLongestWord("HELLO, world she said", "HELLO");
testLongestWord("hello world! she said???", "hello");
testLongestWord("\"hello world!\", she said.", "hello");
testLongestWord("easy as abc123", "abc123");
testLongestWord("easy as abc,123", "easy");
System.out.println("\nTesting empty cases\n");
testLongestWord("", "");
testLongestWord("!", "");
testLongestWord(" ", "");
testLongestWord("\t", "");
testLongestWord(" ", "");
testLongestWord("# $ ? % !", "");
System.out.println("\nTesting edge cases\n");
testLongestWord("a", "a");
testLongestWord("abc", "abc");
testLongestWord("abc d e f ghi", "abc");
testLongestWord("a a b cc dd abc", "abc");
testLongestWord("\"a a b cc dd abc.\"", "abc");
System.out.println("\nTesting apostrophes and dashes\n");
testLongestWord("this isn't five chars", "chars");
testLongestWord("this should've been eight chars said the computer", "should've");
testLongestWord("'this should've been eight chars', said the computer", "should've");
testLongestWord("'hello world!', she said softly.", "softly");
testLongestWord("topsy-turvy is a tenletter word", "topsy-turvy");
testLongestWord("topsy-turvy should not be incorrectly eleven characters", "incorrectly");
testLongestWord("---in-between-these---", "in-between-these");
testLongestWord("---in---between---these---", "between");
testLongestWord("here-is-an-edge-case but a muchmuchlongerword", "muchmuchlongerword");
testLongestWord("d-o-n't-g-o-o-v-e-r-t-h-e-e-d-g-e with muchmuchlongerwords", "muchmuchlongerwords");
testLongestWord("two=five-3 isn't three", "three");
System.out.println("\nThese tests will be opposite in the C version\n");
testLongestWord("the word antidisestablishmentarianism is very long but not as long as 'Llanfairpwllgwyngyllgogerychwyrndrobwyll-llantysiliogogogoch'.", "Llanfairpwllgwyngyllgogerychwyrndrobwyll-llantysiliogogogoch");
testLongestWord("the word antidisestablishmentarianism is very long but not as long as 'Llanfairpwllgwyngyllgogerychwyrndrobwyll-llantysiliogogogoch'.", "antidisestablishment");
testLongestWord("Java strings may contain \0 in the interior", "interior");
testLongestWord("C strings cannot contain \0 in the interior", "strings");
System.out.println("\nTotal number of tests executed: " + testsExecuted);
System.out.println("Number of tests passed: " + (testsExecuted - testsFailed));
System.out.println("Number of tests failed: " + testsFailed);
}
public static void testLongestWord(String line, String expected)
{
String result = longestWord(line);
if (result.equals(expected))
{
System.out.println("Passed: '" + result + "' from '" + line + "'");
}
else
{
System.out.println("FAILED: '" + result + "' instead of '" + expected + "' from '" + line + "'");
testsFailed++;
}
testsExecuted++;
}
public static String longestWord(String line)
{
int pos = 0;
String longest = "";
int longestLength = 0;
String current = "";
int currentLength = 0;
char ch;
line += ' ';
while (pos < line.length())
{
ch = line.charAt(pos);
if ((ch == '\'' || ch == '-') && pos > 0 &&
Character.isLetter(line.charAt(pos - 1)) &&
Character.isLetter(line.charAt(pos + 1)))
{
current += ch;
}
else if (Character.isLetterOrDigit(ch))
{
current += ch;
currentLength++;
}
else
{
if (currentLength > longestLength)
{
longest = current;
longestLength = currentLength;
}
current = "";
currentLength = 0;
}
pos++;
}
return longest;
}
}
我正在进行的我的C转换：
#include <stdio.h>
#include <ctype.h>
#include <string.h>
static int testsExecuted = 0;
static int testsFailed = 0;
char testLongestWord(char line[], char expected[]);
void longestWord(char line[]);
int main(int args, char *argv[]){
printf("%s\n", "Testing typical cases, including punctuation\n");
testLongestWord("the quick brown foxes jumped over the lazy dogs", "jumped");
testLongestWord("hello world she said", "hello");
testLongestWord("Hello\tworld\tshe\tsaid", "Hello");
testLongestWord("HELLO, world she said", "HELLO");
testLongestWord("hello world! she said???", "hello");
testLongestWord("\"hello world!\", she said.", "hello");
testLongestWord("easy as abc123", "abc123");
testLongestWord("easy as abc,123", "easy");
printf("\n%s\n", "Testing empty cases\n" );
testLongestWord("", "");
testLongestWord("!", "");
testLongestWord(" ", "");
testLongestWord("\t", "");
testLongestWord(" ", "");
testLongestWord("# $ ? % !", "");
printf("\n%s\n", "Testing edge cases\n" );
testLongestWord("a", "a");
testLongestWord("abc", "abc");
testLongestWord("abc d e f ghi", "abc");
testLongestWord("a a b cc dd abc", "abc");
testLongestWord("\"a a b cc dd abc.\"", "abc");
printf("\n%s\n", "Testing apostrophes and dashes\n" );
testLongestWord("this isn't five chars", "chars");
testLongestWord("this should've been eight chars said the computer", "should've");
testLongestWord("'this should've been eight chars', said the computer", "should've");
testLongestWord("'hello world!', she said softly.", "softly");
testLongestWord("topsy-turvy is a tenletter word", "topsy-turvy");
testLongestWord("topsy-turvy should not be incorrectly eleven characters", "incorrectly");
testLongestWord("---in-between-these---", "in-between-these");
testLongestWord("---in---between---these---", "between");
testLongestWord("here-is-an-edge-case but a muchmuchlongerword", "muchmuchlongerword");
testLongestWord("d-o-n't-g-o-o-v-e-r-t-h-e-e-d-g-e with muchmuchlongerwords", "muchmuchlongerwords");
testLongestWord("two=five-3 isn't three", "three");
printf("\n%s\n", "These tests will be opposite in the C version\n");
testLongestWord("the word antidisestablishmentarianism is very long but not as long as 'Llanfairpwllgwyngyllgogerychwyrndrobwyll-llantysiliogogogoch'.", "Llanfairpwllgwyngyllgogerychwyrndrobwyll-llantysiliogogogoch");
testLongestWord("the word antidisestablishmentarianism is very long but not as long as 'Llanfairpwllgwyngyllgogerychwyrndrobwyll-llantysiliogogogoch'.", "antidisestablishment");
testLongestWord("Java strings may contain \0 in the interior", "interior");
testLongestWord("C strings cannot contain \0 in the interior", "strings");
printf("Total number of test executed: %d\n", testsExecuted );
printf("number of test passed: %d\n", (testsExecuted - testsFailed));
printf("Number of test failed: %d\n", testsFailed );
//longestWord("Java strings may contain \0 in the interior");
}
char testLongestWord(char line[], char expected[]){
char result[200];
/*longestWord(line);*/
strcpy(result, line);
//char *result = longestWord(line);
//printf("%s\n", line );
//int ret = strcmp(result,expected);
if(strcmp(result,expected)){ // function returns 0 if they are equal
printf("passed: '%s' from '%s'\n", result, line);
}else{
printf("FAILED: '%s' from '%s'\n", expected, result);
testsFailed++;
}
testsExecuted++;
return 0;
}
void longestWord(char line[]){
char longest[200];
int pos = 0;
int longestLength = 0;
char current[300];
int currentLength = 0;
char ch;
size_t maxPos = strlen(line);
while(pos < maxPos){
ch = line[pos++];
for(pos = 0; pos < maxPos;pos++){
ch = line[pos++];
if((ch == '\'' || ch == '-') && (pos > 0) && isalpha(line[pos-1]) && isalpha(line[pos+1])){
strcpy(current, &ch);
}else if(isalpha(ch) || isdigit(ch)){
strcpy(current, &ch);
currentLength++;
//printf("%s\n", longest );
}else{
if(currentLength > longestLength){
strcpy(longest,current);
longestLength = currentLength;
}
//strcpy(current, "");
currentLength =0;
}
}
}
}
错误和警告我正在编辑：我不再有这些错误了。
我在java到c中遇到这行String result = longestWord(line);的问题，函数longestWords没有将结果传递给结果。有办法吗？
答案 0 :(得分：1)
关于在C中混淆数组和指针有很多错误，并且没有任何一件事我可以指出并说如果你改变了它，那么一切都会开始工作，甚至你会看到如何继续前进。
你需要后退一步并开始学习C概念 - 特别是指针和数组如何在C中工作，以及如何安全地在两者之间移动。只有当你真正理解C如何处理内存，以及如何从第一原则编写正确的C程序时，你才能开始考虑如何将一个有效的Java程序转换为一个可用的C程序。
尝试此答案以获取更多信息 - Tutorial on C pointers and arrays from a Java standpoint
答案 1 :(得分：1)
将C字符串设置为像这样的字符数组
char result[] = <something>;
<something>时才允许，即
在您的情况下，您应该使用char *，一个指向字符的指针，因为这是您的longestWord函数应根据代码的逻辑返回的内容（请参阅下面的解决方案）：
char *result = longestWord(line);
就“隐式声明”错误而言，您需要做的就是在代码顶部添加#include的缺少的头文件。
一旦你的程序开始编译，它将展示未定义的行为（即随机崩溃，或者可能不是随机的），因为你的代码试图写入字符串文字的内存。例如
strcat(line, " ");
会尝试在原始调用中传入的句子中添加空格。由于句子是字符串文字，因此不允许写入。
此外，没有简单的方法可以在不使用动态内存分配的情况下从函数返回C字符串。更好的方法是将缓冲区传递给调用者的最长单词，并将其填入函数内部，如下所示：
void longestWord(char line[], char longestBuf[], size_t bufSize)
调用者必须提供一个足够长度的可写char[]数组，并在其中写入结果。