Cの関数のポインタの動作が正しくない

Question

次のプログラムに問題があります。

main関数は、関数returnArrayOfWords(arrS1, &ptrArray1)を2回呼び出します。最初の呼び出しでは、配列は完全に解析され、その後、ポインタは常に最初の単語を指します。一方、2番目の呼び出しの後、1番目の配列のポインタは、2番目の単語、3番目の単語、または時には最初の単語を指しますが、常に最初の単語を指す必要があります。

なぜ2回目に呼び出されたときに関数が正しく動作しないのですか？

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

void returnArrayOfWords (char *str4Parsing, char *arrayParsed[]) 
{ 
    char seps[] = " ,\t\n"; // separators 
    char *token1 = NULL; 
    char *next_token1 = NULL; 
    int i = 0; 

    // Establish string and get the first token: 
    token1 = strtok_s(str4Parsing, seps, &next_token1); 

    // While there are tokens in "str4Parsing" 
    while (token1 != NULL) 
    { 
     // Get next token: 
     if (token1 != NULL) 
     { 
      arrayParsed[i] = token1; 
      printf(" %s\n", token1); 
      token1 = strtok_s(NULL, seps, &next_token1); 
      i++; 
     } 
    } 
} 


//int main1() 
int main() 
{ 
    int i, j, n = 80; /*max number of words in string*/ 
    char arrS1[80], arrS2[80]; 
    const char *w1, *w2; /*pointers*/ 
    char *ptrArray1, *ptrArray2; 
    int currLength1 = 0, currLength2 = 0 ; 
    int sizeArr1 = 0, sizeArr2 = 0; 
    int maxLength = 0; 
    char wordMaxLength ; 

    printf("Type your first string: "); 
    fgets(arrS1, 80, stdin); 
    returnArrayOfWords(arrS1, &ptrArray1); 
    sizeArr1 = sizeof(ptrArray1)/sizeof(ptrArray1[0]); 

    printf("Type your second string: "); 
    fgets(arrS2, 80, stdin); 
    returnArrayOfWords(arrS2, &ptrArray2); 
    sizeArr2 = sizeof(ptrArray2)/sizeof(ptrArray2[0]); 

    for (i = 0; i < sizeArr1; i++) 
    { 
     // to find the largest word in the array 
     w1 = &ptrArray1[i]; 
     currLength1 = strlen(w1); 
     for (j = 0; j < sizeArr2; j++) 
     { 
      w2 = &ptrArray2[j]; 
      currLength2 = strlen(w2); 

      if (strcoll(w1, w2) == 0) 
      // compares the strings 
      { 
       if (currLength2 >= maxLength) 
       // in the 0th element -> the length of the longest word 
       { 
        maxLength = currLength2; 
        wordMaxLength = ptrArray2[j]; 
       } 
      } 
     } 
    } 

    printf("The largest word is: %s", wordMaxLength); 
    return 0; 
} 

はEDIT：

ここでは、コードの最新バージョンだ、ここですべてが正常に動作し、それを自分自身を修正するために管理。私は誰かが解決策としてそれを必要とする場合に備えて転記しています：

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

     #define n 80 /*max number of words in string*/ 

     /* Arrays and pointers */ 

     int returnArrayOfWords (char *str4Parsing, char *arrayParsed[]) 
    { 
// returns the length of array 
int elArr = 0, na = 0; 
char *delim = " .,;-\t\n";  /* word delimiters */ 
char *next_token1 = NULL; 
char *ap = str4Parsing;   /* pointer to str4Parsing */ 
for (ap = strtok_s (str4Parsing, delim, &next_token1); ap; ap = strtok_s(NULL, delim, &next_token1)) 
{ 
    arrayParsed[na++] = ap; 
    elArr++; 
} 

return elArr; 
} 


void printArr(char *arr[]) 
{ 
int i; 
for (i = 0; i < n; i++) 
{ 
    printf("Element %d is %s \n", i, arr[i]); 
} 
} 


void findLargestWord(char *ptrArray1[], int sizeArr1, char *ptrArray2[], int  sizeArr2) 
{ 
size_t maxLength = 0; 
char *wordMaxLength = NULL ; 
int i = 0, j = 0; 
char *w1 = NULL, *w2 = NULL; /*pointers*/ 
size_t currLength1 = 0, currLength2 = 0 ; 

for (i = 0; i < sizeArr1; i++) 
    { 
    // to find the largest word in the array 
    w1 = (ptrArray1[i]); // value of address (ptrArray1 + i) 
    currLength1 = strlen(w1); 
    //printf("The word from the first string is: %s and its length is : %d  \n", w1, currLength1); // check point 

    for (j = 0; j < sizeArr2; j++) 
     { 
     w2 = (ptrArray2[j]); // value of address (ptrArray2 + j) 
     currLength2 = strlen(w2); 
     //printf("The word from the second string is : %s and its length is : %d \n", w2, currLength2); // check point 

     if (strcoll(w1, w2) == 0 && currLength1 == currLength2) 
      // compares the strings 
      { 
      if (currLength2 >= maxLength) 
       // in the variable maxLength -> the length of the longest word 
       { 
        maxLength = currLength2; 
        wordMaxLength = w2; 
        //printf("The largest word for now is : %s and its length is : %d \n", wordMaxLength, maxLength); // check point 
       } 
      } 
     } 
    } 
printf("The largest word is: %s \n", wordMaxLength); 
printf("Its length is: %d \n", maxLength); 
} 


    void typeArray (char *arrS1) 
{ 
    int err = 0; 
if (!fgets (arrS1, n, stdin)) { /* validate 'arrS1' */ 
    fprintf (stderr, "Error: invalid input for string.\n"); 
    err = 1; 
} 

while (err == 1) 
{ 
    if (!fgets (arrS1, n, stdin)) { /* validate 'arrS1' */ 
     fprintf (stderr, "Error: invalid input for string.\n"); 
     err = 1; 
    } 
} 
} 


    int main(void) 
{ 
    char arrS1[n], arrS2[n]; 
char *ptrArray1[n] = {NULL}, *ptrArray2[n] = {NULL}; 
int sizeArr1 = 0, sizeArr2 = 0; 

printf("Type your first string: "); 
typeArray (arrS1); 
sizeArr1 = returnArrayOfWords (arrS1, ptrArray1); // sizeArr1 = number of elements in array 1 

printf("Type your second string: "); 
typeArray (arrS2); 
sizeArr2 = returnArrayOfWords (arrS2, ptrArray2); // sizeArr2 = number of elements in array 2 

findLargestWord(ptrArray1, sizeArr1, ptrArray2, sizeArr2); 

return 0; 
} 

Answer 1

警告なしでコンパイルされていますが、プログラムに多数のエラーがあります。主に配列のポインタ型と割り当てられたメモリ。次に、関数はいくつの単語が許されているかを知らず、読み込まれた単語の数を返しません - あなたのメソッドは（コメントのように）まったく機能しませんでした。第3に、文字列の比較：あなたは明確に目標を述べなかったが、コメントでは "最大の文字列"を望む。 strcollそれはしません - それは字句比較ですので、私はあなたが入力する2つの文の最長の文字列を見つけるためにそのセクションを変更しました。コメントを見る、私は多くの変更を加えた。

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

int returnArrayOfWords (char *str4Parsing, char *arrayParsed[], int maxtokens) // added max 
{ 
    char seps[] = " ,\t\n"; // separators 
    char *token1 = NULL; 
    char *next_token1 = NULL; 
    int i = 0; 

    // Establish string and get the first token: 
    token1 = strtok_s(str4Parsing, seps, &next_token1); 

    // While there are tokens in "str4Parsing" 
    while (token1 != NULL) 
    { 
     if(i >= maxtokens) 
      return i;         // ignore the rest 
     arrayParsed[i] = token1; 
     printf(" %s\n", token1); 
     token1 = strtok_s(NULL, seps, &next_token1); 
     i++; 
    } 
    return i; 
} 

int main (void)           // correct signature 
{ 
    int i, j, n = 80; /*max number of words in string*/ 
    char arrS1[80], arrS2[80]; 
    //const char *w1, *w2; /*pointers*/     // deleted 
    char **ptrArray1, **ptrArray2;      // changed type 
    int currLength1 = 0, currLength2 = 0 ; 
    int sizeArr1 = 0, sizeArr2 = 0; 
    int maxLength = 0; 
    char *wordMaxLength;        // changed to pointer 

    ptrArray1 = malloc(n * sizeof (char*));    // allocate mem for pointer array 
    if (ptrArray1 == NULL) 
     return 1; 
    ptrArray2 = malloc(n * sizeof (char*));    // allocate mem for pointer array 
    if (ptrArray2 == NULL) 
     return 1; 

    printf("Type your first string: "); 
    fgets(arrS1, 80, stdin); 
    sizeArr1 = returnArrayOfWords(arrS1, ptrArray1, n); // indirection error, added max words, get actual num 

    printf("Type your second string: "); 
    fgets(arrS2, 80, stdin); 
    sizeArr2 = returnArrayOfWords(arrS2, ptrArray2, n); // indirection error, added max words, get actual num 

    for (i = 0; i < sizeArr1; i++)      // this section rewritten 
    { 
     // to find the largest word in the array 
     currLength1 = strlen(ptrArray1[i]); 
     if(currLength1 > maxLength) 
     { 
      maxLength = currLength1; 
      wordMaxLength = ptrArray1[i];    // changed definition to pointer 
     } 
    } 

    for (j = 0; j < sizeArr2; j++) 
    { 
     // to find the largest word in the array 
     currLength2 = strlen(ptrArray2[j]); 
     if(currLength2 > maxLength) 
     { 
      maxLength = currLength2; 
      wordMaxLength = ptrArray2[j];    // changed definition to pointer 
     } 
    } 

    printf("The largest word is: %s", wordMaxLength); 

    free(ptrArray1);         // added 
    free(ptrArray2); 
    return 0; 
} 

プログラムセッション：

Type your first string: one two three four 
one 
two 
three 
four 
Type your second string: apple banana pear 
apple 
banana 
pear 
The largest word is: banana