Question

我想通过字符串删除字母g，不使用任何内置函数，只使用一个变量，必须是指针，不允许使用括号。我有代码，但它一直返回一个空字符串而不是新编辑的字符串。

#include <iostream>

using namespace std;


void deleteG(char *str) {
    char *temp = str; //make new pointer,pointing at existing, now i have initialized and enough size.

    while (*str != '\0') { //while the c-string does not reach null termination

        if (*str != 'g' || *str != 'G') { // if the value of the current position is not the character g or G proceed.
            *temp = *str;//copy value over
            temp++;//increase count
        }
        str++;//increase count to next char and check again above is if does not equal g or G
    }
//this should now copy the new string over to the old string overriding all characters 
    while (*temp != '\0') {
        *str = *temp;
        str++;
        temp++;

    }

}

int main() {
    char msg[100] = "I recall the glass gate next to Gus in Lagos, near the gold bridge.";
    deleteG(msg);
    cout << msg;  // prints   I recall the lass ate next to us in Laos, near the old bride.
}

Answer 1

if (*str != 'g' || *str != 'G') {

此条件始终为true，因此始终复制角色。

为什么总是这样，你问？

想一想 - 这个角色是g，或G，或其他东西。

如果是g，则*str != 'g'为false，*str != 'G'为真，且false || true为真，则条件为真。

如果是G，则*str != 'g'为真，*str != 'G'为假，且true || false为真，则条件为真。

如果是其他内容，则*str != 'g'为真，*str != 'G'为真，且true || true为真，则条件为真。

Answer 2

将其更改为：

<%= form_tag users_path, method: :get do %>    
  <%= select_tag :sort_type, options_for_select(User.sort_types, :selected => params[:sort_type]), :include_blank => true %>  
<% end %>

class User
  enum sort_type: ["popularity", "number of photos"]
end

此条件检查字母不 g，无论是否为案件。

c字符串复制无法清空字符串

2 个答案: