Question

我试图在C中编写将采用字符串的代码，检查每个字符是否为特定字符（称之为'x'），如果字符为'x'，则更改它多个字符（如"yz"）。这是我的尝试，假设缓冲区和替换是定义的字符数组（即char buffer[400] = jbxyfgextd...; char replace[250];）

  int j = 0;
  for (j = 0; j < 110; j++) {
    if (buffer[j]=='x') {
      int len = strlen(replace);
      replace[len] = 'y';
      replace[len+1] = 'z';
    }
    else {
      replace[j]=buffer[j];
    }
  }

当我运行此功能时，我会收到一些y和z，但它们并非背靠背。是否有任何程序/功能可以轻松完成这项工作？

Answer 1

因为buffer[]和replace[]数组中的索引不相同。分别使用两个索引。

在您的代码表达式中：replace[j] = buffer[j];错误。你可以纠正它：

 else {
      int len = strlen(replace);
      replace[len]=buffer[j];
 }

但要使用strlen()，数组replace[]应该以nul \0终止。（声明替换为char replace[250] = {0}）

修改：

要编写更好的代码，请使用上面建议的两个septate索引 - 代码将高效且简化。

int bi = 0;  // buffer index 
int ri = 0;  // replace index 
for (bi = 0; bi < 110; bi++) {
    if (buffer[bi] == 'x') {      
      replace[ri++] = 'y';
      replace[ri] = 'z';
    }
    else {
      replace[ri] = buffer[bi];
    }
    replace[++ri] = '\0'; // terminated with nul to make it string   
}

Answer 2

#include <iostream>
#include <string>
#include <cstring>

int main ( int argc, char *argv[])
{

  // Pass through the array once counting the number of chars the final string
  // will need then allocate the new string

  char buffer[] = "this x is a text test";

  char replacement[] = "yz";
  unsigned int replaceSize = strlen(replacement);

  unsigned int bufferSize = 0;
  unsigned int newSize = 0;

  // calculate the current size and new size strings
  // based on the replacement size

  char *x = buffer;
  while (*x)
  {
    if ( *x == 'x' )
    {
      newSize+=replaceSize;
    }
    else
    {
      ++newSize;
    }
    ++x;
    ++bufferSize;
  }

  // allocate the new string with the new size 
  // and assign the items to it
  char *newString = new char[newSize];
  unsigned int newIndex = 0;
  for ( unsigned int i = 0; i < bufferSize; ++i )
  {
    if ( buffer[i] == 'x' )
    {
      for ( unsigned int j = 0; j < replaceSize ; ++j )
      {
        newString[newIndex++] = replacement[j];
      }
    }
    else
    {
      newString[newIndex++] = buffer[i];
    }
  }

  std::string originalS ( buffer );
  std::string newS ( newString );

  std::cout << "Original: " << originalS << std::endl;
  std::cout << "New: " << newS << std::endl;

  delete newString;

}

将字符串中的字符更改为字符串

2 个答案: