如何從c中的段落中刪除字符？

Question

我編寫了一個ac程序，該程序從字符串中除去一個字符，而不是從多行中除去一個字符，然后編寫代碼以存儲一個字符串的多行，但是在編譯代碼時，我無法獲得正確的輸出。 請有人看看。

#include <stdio.h>

int main()
{
    char inputString[1000], ch, outputString[1000];

    int i,j=0;

    printf ("Enter a multi line string:\n");
    scanf ("%[^;]s", inputString);
    gets(inputString);

    printf ("Enter a letter to be removed:\n");
    scanf ("%c", &ch);
    for (i=0; inputString[i]!='\0';i++)
    {
        if(inputString[i]==ch)
        {
            outputString[j]=inputString[i+1];
            i++;
        }
        else
        {
            outputString[j]=inputString[i];
        }
        j++;
    }
    for (i=0;i<j;i++)
    {
        printf ("%c", outputString[i]);
    }
    return 0;
}

Answer 1

您的程序中有幾個問題

1）與

scanf ("%[^;]s", inputString);
gets(inputString);

例如，如果輸入是foo bar loop;則用scanf之后的gets重寫inputString foo bar loop; 您可以通過foo bar loop設置inputString ，然后使用再次設置它; 所以你失去了scanf的全部

2） scanf和gets都可以從inputString寫入，您沒有任何保護，可以給scanf讀取最大大小，並且可以用fgets代替gets的使用（忘記您在inputString中重寫的事實）

3）您永遠不會考慮EOF情況，總是假設輸入了

4進

    if(inputString[i]==ch)
    {
        outputString[j]=inputString[i+1];
        i++;
    }
    else
    {
        outputString[j]=inputString[i];
    }
    j++;

outputString[j]=inputString[i+1]; 假設您從來沒有連續兩次刪除該字符，那么這樣做是錯誤的。

5）要使用固定大小的陣列不是強制性的，分配陣列然后在需要時的realloc

6）在

for (i=0;i<j;i++)
{
    printf ("%c", outputString[i]);
}

更好的結束outputString以空字符，只是通過的fputs打印或提出添加最后\\ n的情況下，它缺少

---

這里有個建議：

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

int main()
{
  char * inputString = NULL;
  size_t sz = 0, used = 0;
  int v;

  printf ("Enter a multi line string (ended by ';'):\n");

  while ((v = getchar()) != ';') {
    if (v == EOF) {
      puts("premature EOF, abort");
      return -1;
    }

    if (used == sz) {
      sz += 100;
      inputString = realloc(inputString, sz);
      if (inputString == NULL) {
        puts("not enough memory");
        return -1;
      }
    }
    inputString[used++] = v;
  }

  /* read up to end of line */
  char * outputString = 0;

  if (getline(&outputString, &sz, stdin) == -1) {
    puts("premature EOF or not enough memory");
    return -1;
  }
  free(outputString);

  printf ("Enter a letter to be removed:\n");

  char ch;

  if (scanf ("%c", &ch) != 1) {
     puts("premature EOF, abort");
     return -1;
  }

  size_t i, j = 0;

  outputString = malloc(used + 1); /* worst case, +1 to have place for null character */

  for (i = 0; i != used; ++i)
  {
    if (inputString[i] != ch)
      outputString[j++] = inputString[i];
  }
  outputString[j] = 0;

  puts(outputString);

  free(inputString);
  free(outputString);

  return 0;
}

編譯與執行：

pi@raspberrypi:/tmp $ gcc -pedantic -Wextra -g l.c
pi@raspberrypi:/tmp $ ./a.out
Enter a multi line string (ended by ';'):
this is a paragraph
  terminated by
a ;!!
Enter a letter to be removed:
i
ths s a paragraph
  termnated by
a 

在valgrind下執行：

pi@raspberrypi:/tmp $ valgrind ./a.out
==3900== Memcheck, a memory error detector
==3900== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==3900== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==3900== Command: ./a.out
==3900== 
Enter a multi line string (ended by ';'):
this is a paragraph
  terminated by
a ;!!
Enter a letter to be removed:
i
ths s a paragraph
  termnated by
a 
==3900== 
==3900== HEAP SUMMARY:
==3900==     in use at exit: 0 bytes in 0 blocks
==3900==   total heap usage: 5 allocs, 5 frees, 2,307 bytes allocated
==3900== 
==3900== All heap blocks were freed -- no leaks are possible
==3900== 
==3900== For counts of detected and suppressed errors, rerun with: -v
==3900== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 6 from 3)