GTK简单版计算器

接下来我们做一个简单版的计算器。

1）获取按钮上的内容。

2）如果获取的内容是“ c ”，则代表进行退格操作，相当于删去最后一个字符。

3）如果获取的内容不是“ c ”，则把每一次获取的内容连接起来，如：

第一次按了 “ 1 ”， 第二次按了 “ + ”， 第三次按了 “ 1 ”， 连起来则变为 “1+1”。

4）如果获取的内容是“ = ”，则需要相应的运算。先把连起来的字符串拆出来，然后再进行相应操作，最后把运算结果重新显示到行编辑上。

完整代码如下：

#include <gtk/gtk.h>  // 头文件
#include <string.h>

char buf[50] = {0};  //全局变量，保存数据

// 按钮的回调函数
void deal_num(GtkButton *button, gpointer data)
{
  const char *txt = gtk_button_get_label( button ); // 获取点击按钮的内容
  
  // 退格操作
  if( 0 == strcmp("c", txt) ){ // 如果是退格键
    buf[strlen(buf) - 1] = 0; // 最后一个字符变为 0
    //gtk_entry_set_text(GTK_ENTRY(data), buf); //重新给行编辑设定内容
    
  }else{
    int a = 0, b = 0;
    char c;
    strcat(buf, txt);  // 内容追加
    
    // 运算操作
    if(0 == strcmp("=", txt) ){  // 如果是 " = "
      sscanf(buf, "%d%c%d", &a, &c, &b);  // 拆包
      printf("a=%d, c = %c, d=%d\n", a, c, b);
      if('+' == c){
        sprintf(buf, "%d", a+b);
      }else if('-' == c){
        sprintf(buf, "%d", a-b);
      }else if('*' == c){
        sprintf(buf, "%d", a*b);
      }else if('/' == c){
        sprintf(buf, "%d", a/b);
      }
    }
  }
  
  gtk_entry_set_text(GTK_ENTRY(data), buf);  // 给行编辑设定内容
  

}


int main( int   argc, char *argv[] ) 
{
  gtk_init (&argc, &argv);  // 初始化
  
  // 窗口的操作
  GtkWidget *window = gtk_window_new (GTK_WINDOW_TOPLEVEL);   // 创建窗口 
  gtk_widget_set_size_request(window, 270, 320);
  
  // 表格的操作
  GtkWidget *table = gtk_table_new(5, 4, TRUE);   // 表格布局，5行4列  
  
  // 行编辑的操作
  GtkWidget *entry = gtk_entry_new();    // 行编辑的创建
  //gtk_entry_set_text(GTK_ENTRY(entry), "2+2=4");  // 给行编辑设置内容
  gtk_editable_set_editable(GTK_EDITABLE(entry), FALSE);// 设置行编辑不允许编辑，只做显示用
  
  // 按钮的操作
  GtkWidget *button0 = gtk_button_new_with_label("0");  // 按钮0
  GtkWidget *button1 = gtk_button_new_with_label("1");  // 按钮1
  GtkWidget *button2 = gtk_button_new_with_label("2");  // 按钮2
  GtkWidget *button3 = gtk_button_new_with_label("3");  // 按钮3
  GtkWidget *button4 = gtk_button_new_with_label("4");  // 按钮4
  GtkWidget *button5 = gtk_button_new_with_label("5");  // 按钮5
  GtkWidget *button6 = gtk_button_new_with_label("6");  // 按钮6
  GtkWidget *button7 = gtk_button_new_with_label("7");  // 按钮7
  GtkWidget *button8 = gtk_button_new_with_label("8");  // 按钮8
  GtkWidget *button9 = gtk_button_new_with_label("9");  // 按钮9
  GtkWidget *button_add = gtk_button_new_with_label("+");      // 加
  GtkWidget *button_minus = gtk_button_new_with_label("-");    // 减
  GtkWidget *button_multiply = gtk_button_new_with_label("*");  // 乘
  GtkWidget *button_divide = gtk_button_new_with_label("/");    // 除
  GtkWidget *button_equal = gtk_button_new_with_label("=");    // 等于
  GtkWidget *button_detele = gtk_button_new_with_label("c");    // 退格
  
  // 布局操作
  gtk_container_add(GTK_CONTAINER(window), table); // 表格放入窗口 
  gtk_table_attach_defaults(GTK_TABLE(table), entry, 0, 4, 0, 1);  // 行编辑放入表格
  gtk_table_attach_defaults(GTK_TABLE(table), button0, 0, 1, 4, 5);  // 按钮放入表格
  gtk_table_attach_defaults(GTK_TABLE(table), button1, 0, 1, 3, 4);
  gtk_table_attach_defaults(GTK_TABLE(table), button2, 1, 2, 3, 4);
  gtk_table_attach_defaults(GTK_TABLE(table), button3, 2, 3, 3, 4);
  gtk_table_attach_defaults(GTK_TABLE(table), button4, 0, 1, 2, 3);
  gtk_table_attach_defaults(GTK_TABLE(table), button5, 1, 2, 2, 3);
  gtk_table_attach_defaults(GTK_TABLE(table), button6, 2, 3, 2, 3);
  gtk_table_attach_defaults(GTK_TABLE(table), button7, 0, 1, 1, 2);
  gtk_table_attach_defaults(GTK_TABLE(table), button8, 1, 2, 1, 2);
  gtk_table_attach_defaults(GTK_TABLE(table), button9, 2, 3, 1, 2);
  gtk_table_attach_defaults(GTK_TABLE(table), button_add, 1, 2, 4, 5);
  gtk_table_attach_defaults(GTK_TABLE(table), button_minus, 2, 3, 4, 5);
  gtk_table_attach_defaults(GTK_TABLE(table), button_multiply, 3, 4, 2, 3);
  gtk_table_attach_defaults(GTK_TABLE(table), button_divide, 3, 4, 3, 4);
  gtk_table_attach_defaults(GTK_TABLE(table), button_equal, 3, 4, 4, 5);
  gtk_table_attach_defaults(GTK_TABLE(table), button_detele, 3, 4, 1, 2);
  
  // 注册信号函数，把 entry 传给回调函数 deal_num()
  g_signal_connect(button0, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button1, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button2, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button3, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button4, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button5, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button6, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button7, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button8, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button9, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button_add, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button_minus, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button_multiply, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button_divide, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button_equal, "pressed", G_CALLBACK(deal_num), entry);
  g_signal_connect(button_detele, "pressed", G_CALLBACK(deal_num), entry);

  gtk_widget_show_all(window);  // 显示所有控件
   
  gtk_main();  //进入事件循环 
   
  return 0; 
}

操作图如下：