试图在C中制作单词搜索程序

Question

如果输入字典从文件中读入以用于所有测试用例和几个单词搜索网格，我想识别字典中出现在每个单词搜索网格中的所有单词。

我已经阅读了dictionary.txt文件，我相信它可以读取任何字母网格，我在找到出现在dictionary.txt文件中的网格中的单词时遇到了麻烦。我决定对所有方向的字符串使用递归二进制搜索，但对我来说有点复杂。

我的程序一直运行，直到它进入单词搜索功能，它试图找到网格中的单词并且它会崩溃，但我不知道为什么而且不确定我是否在正确的轨道上。

这是我认为错误的作品，

int binsearch(char** dictionary, char** puzzle, int low, int high){

int mid;

if(low == 0 && high == 0){
    return 0;
}

mid = (low+high)/2 ;

if(strcmp(*puzzle,dictionary[mid]) == 0){
        //found a match
    return 1;
}

else if(strcmp(*puzzle,dictionary[mid]) > 0){
        //check upper half
    return binsearch(dictionary,puzzle,mid+1,high);
}

else if(strcmp(*puzzle,dictionary[mid]) < 0){
    //check lower half
    return binsearch(dictionary,puzzle,low,mid-1);
}
else return 0;

}

char wordSearch(char** dictionary, char** puzzle, int row, int col){

int i, X, Y, dir = 0;
char* wordsfound[20]= {'\0'};
for (X=0;X<row+1;X++){
    for(Y=0;Y<col;Y++){
        for(dir=0;dir<DX_SIZE;dir++) //check every direction
            for(i=0;i<19;i++){
                //will continue in direction DX,DY starting at x,y
                int nextX = X + DX[dir] * i;
                int nextY = Y + DY[dir] * i;
                if(nextX < 0 || nextX >= row) break; //keep in bounds
                if(nextY < 0 || nextY >= col) break;
                //store the string of letters
                *wordsfound[i] = (puzzle[nextX][nextY]);
                if(i>2){ //minimum word is 3
                //if the string of letters is actually a word, print
                    int bin = binsearch(dictionary,wordsfound,1,listlength);
                    if(bin){
                        printf("%s\n",wordsfound);
                    }
                }
            }
    }
}

}

但这是我的整个代码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define listlength 149256
#define maxWordLen 19


char** getWords(int rows, int cols);
void freeArray(char** array, int rows);
char** makeGridArray(int rows, int cols);
int binsearch(char** dictionary, char** puzzle, int low, int high);
char wordSearch(char** dictionary, char** puzzle, int row, int col);
const int DX_SIZE = 8;
const int DX[] = {-1,-1,-1,0,0,1,1,1};
const int DY[] = {-1,0,1,-1,1,-1,0,1};

int main(){

    //read in dictionary
    int i,j,x=0, numCases, gridRow, gridCol;
    char** words = getWords(listlength, maxWordLen);

    //Get number of cases.

    printf("enter number of cases:\n");
    scanf("%d", &numCases);

    //process each case.

    while(x < numCases){

        scanf("%d%d",&gridRow,&gridCol);

        //make word search grid
        char** grid = makeGridArray(gridRow+1, gridCol);

        /* for testing if grid is storing properly

        for(i=0; i<gridRow+1;i++){
            printf("%s\n",grid[i]);
        }

        */
        printf("Words Found Grid #%d:",x+1);
        wordSearch(words, grid, gridRow+1, gridCol);
        x++;
        freeArray(grid,gridRow+1);
    }
    freeArray(words, listlength);

}


char** getWords(int rows, int cols){

    int i;

    //allocate top level of pointers.
    char** words = malloc(sizeof(char*)*rows);

    //allocate each individual array
    for(i=0; i<rows; i++){
        words[i] = malloc(sizeof(char)*cols+1);
    }

    //read dictionary.txt
    FILE *dictionary = fopen("dictionary.txt", "r");
    for(i=0; i<rows; i++){
        fgets(words[i], cols+1,dictionary);
    }

    fclose(dictionary);
    return words;
}

char** makeGridArray(int rows, int cols){

    //allocate top level of pointers.
    char** grid = malloc(sizeof(char*)*rows);
    int i,j;

    //allocate each individual array
    for(i=0; i<rows;i++){
        grid[i] = malloc(sizeof(char)*cols+1);
    }
    //read in user input grid
    for(i=0;i<rows;i++){
        gets(grid[i]);
    }
    return grid;
}

int binsearch(char** dictionary, char** puzzle, int low, int high){

    int mid;

    if(low == 0 && high == 0){
        return 0;
    }

    mid = (low+high)/2 ;

    if(strcmp(*puzzle,dictionary[mid]) == 0){
            //found a match
        return 1;
    }

    else if(strcmp(*puzzle,dictionary[mid]) > 0){
            //check upper half
        return binsearch(dictionary,puzzle,mid+1,high);
    }

    else if(strcmp(*puzzle,dictionary[mid]) < 0){
        //check lower half
        return binsearch(dictionary,puzzle,low,mid-1);
    }
    else return 0;

}

char wordSearch(char** dictionary, char** puzzle, int row, int col){

    int i, X, Y, dir = 0;
    char* wordsfound[20]= {'\0'};
    for (X=0;X<row+1;X++){
        for(Y=0;Y<col;Y++){
            for(dir=0;dir<DX_SIZE;dir++) //check every direction
                for(i=0;i<19;i++){
                    //will continue in direction DX,DY starting at x,y
                    int nextX = X + DX[dir] * i;
                    int nextY = Y + DY[dir] * i;
                    if(nextX < 0 || nextX >= row) break; //keep in bounds
                    if(nextY < 0 || nextY >= col) break;
                    //store the string of letters
                    *wordsfound[i] = (puzzle[nextX][nextY]);
                    if(i>2){ //minimum word is 3
                    //if the string of letters is actually a word, print
                        int bin = binsearch(dictionary,wordsfound,1,listlength);
                        if(bin){
                            printf("%s\n",wordsfound);
                        }
                    }
                }
        }
    }

}


void freeArray(char** array, int rows){
    //free arrays
    int i;
    for(i=0; i<rows; i++){
        free(array[i]);
    }
    free(array);
}

Answer 1

你有

char* wordsfound[20]= {'\0'};

以上只会使所有20 char pointers指向NULL。

然后你解除引用

*wordsfound[i] = (puzzle[nextX][nextY]);

因此，它会崩溃，因为wordsfound[i]为NULL。

修改 所以，你必须改变wordsfound的声明。 如果按照@John Hascall和@ J V A的建议将其更改为char wordsfound [20]， 那么你需要这样做：

char wordSearch(char** dictionary, char** puzzle, int row, int col){

    int i, X, Y, dir = 0;
    char wordsfound[20]= {'\0'};
    for (X=0;X<row+1;X++){
        for(Y=0;Y<col;Y++){
            for(dir=0;dir<DX_SIZE;dir++) //check every direction
                for(i=0;i<19;i++){
                    //will continue in direction DX,DY starting at x,y
                    int nextX = X + DX[dir] * i;
                    int nextY = Y + DY[dir] * i;
                    if(nextX < 0 || nextX >= row) break; //keep in bounds
                    if(nextY < 0 || nextY >= col) break;
                    //store the string of letters
                    wordsfound[i] = (puzzle[nextX][nextY]);
                    if(i>2){ //minimum word is 3
                        wordsfound[i+1]= '\0'; // yes you need null char before passing to binsearch for strcmp to work.
                        //if the string of letters is actually a word, print
                        int bin = binsearch(dictionary, &wordsfound,1,listlength);
                        if(bin){
                           printf("%s\n",wordsfound);
                        }
                    }
                }

            }
        }

    }

<强>即。您需要将&wordsfound传递给binsearch，因为binsearch将char **作为第二个参数。

您可以传递wordsfound，但在这种情况下，请将binsearch函数的第二个参数更改为char * puzzle，并使用puzzle中的strcmp代替*puzzle在binsearch内{1}}。

但是，如果你的目标不是像JVA先生那样将单个角色传递给binsearch，那么你需要采取不同的方式。在这种情况下，您需要使用2-d char数组或指向char数组的指针。在这种情况下，您需要更改wordsearch中的当前代码。如果您使用pointer to a char array，则需要分配内存。

Answer 2

下面：

has

应该是：

    char* wordsfound[20]= {'\0'};
    for (X=0;X<row+1;X++){
        for(Y=0;Y<col;Y++){
            for(dir=0;dir<DX_SIZE;dir++) //check every direction
                for(i=0;i<19;i++){
                    ...
                    *wordsfound[i] = (puzzle[nextX][nextY]);

此外，在检查上半部分或下半部分的binsearch函数中，您需要确保 char wordsfound[20]= {'\0'}; /* not 20 pointers! */ for (X=0;X<row+1;X++){ for(Y=0;Y<col;Y++){ for(dir=0;dir<DX_SIZE;dir++) //check every direction for(i=0;i<19;i++){ ... wordsfound[i] = (puzzle[nextX][nextY]); /* no '*' */ wordsfound[i+1] = '\0'; /* end the string */ 和mid+1分别仍然是数组中的有效索引。如果访问数组边界之外的元素，那么坏事就等着你。

例如，如果mid-1和low = 0：

high = 1

所以你要比较数组元素0并决定你需要查看下半部分，现在你用mid = (low+high)/2 ; /* this is zero */ 作为mid-1来调用。哦，不！！