你能帮我做一下这个算法"向右或向左移动一个字符串"

Question

我正在研究一个使用PIC18,LCD等实现时钟的项目,我正在使用mikroC来实现这个项目.

但是,我不擅长C而且我在某些方面陷入困境.时钟有一个菜单,有多个选项,可以让用户设置时间,闹钟,闹钟声等.菜单包含以下内容:

1. Set Time
2. Add Alarm
3. Select Alarm
4. Add New Tone
5. Select Tone
6. EXIT

时钟有3个按钮,OK,RIGHT,和LEFT.当时钟开机时,它将Set Time默认显示在LCD上.我想添加一个功能,当我按下RIGHT按钮它应该显示Add Alarm但逐渐不直接.我在菜单中有6个项目,所以我必须逐步进行12次运动(右侧6个,左侧6个).我试过这个如下:

 Lcd_Out(2, 2, "   set Time   ");
 Delay_ms(50);
 Lcd_Out(2, 2, "  set Time    ");
 Delay_ms(50);
 Lcd_Out(2, 2, " set Time     ");
 Delay_ms(50);
 Lcd_Out(2, 2, " et Time      ");
 Delay_ms(50);
 Lcd_Out(2, 2, " t Time       ");
 Delay_ms(50);
 Lcd_Out(2, 2, " Time         ");
 Delay_ms(50);
 Lcd_Out(2, 2, " ime          ");
 Delay_ms(50);
 Lcd_Out(2, 2, " me           ");
 Delay_ms(50);
 Lcd_Out(2, 2, " e            ");
 Delay_ms(50);
 Lcd_Out(2, 2, "              ");
 Delay_ms(50);
 Lcd_Out(2, 2, "              ");
 Delay_ms(50);
 Lcd_Out(2, 2, "              ");
 Delay_ms(50);
 Lcd_Out(2, 2, "              ");
 Delay_ms(50);
 Lcd_Out(2, 2, "            A ");
 Delay_ms(50);
 Lcd_Out(2, 2, "           Ad ");
 Delay_ms(50);
 Lcd_Out(2, 2, "          Add ");
 Delay_ms(50);
 Lcd_Out(2, 2, "         Add  ");
 Delay_ms(50);
 Lcd_Out(2, 2, "        Add A ");
 Delay_ms(50);
 Lcd_Out(2, 2, "       Add Al ");
 Delay_ms(50);
 Lcd_Out(2, 2, "      Add Ala ");
 Delay_ms(50);
 Lcd_Out(2, 2, "     Add Alar ");
 Delay_ms(50);
 Lcd_Out(2, 2, "    Add Alarm ");
 Delay_ms(50);
 Lcd_Out(2, 2, "   Add Alarm  ");
 Delay_ms(50);
 Lcd_Out(2, 2, "  Add Alarm   ");

这是一个动作,为了完成其他动作,我需要大量代码,而PIC的RAM是有限的.那么,你们能帮助我解决这个问题吗？

Answer 1

你需要这样的东西:

#define STRSZ 14
//           <------------><------------>
char *str = "   set Time     Add Alarm   ";    // Two 14-char strings.
char disp[STRSZ+1];                            // Buffer for holding display string.
for (i = 0; i <= STR_SZ; i++) {                // Starting character to use.
    memcpy (disp, &(str[i]), STR_SZ);          // Copy the relevant bit.
    disp[STR_SZ] = '\0';                       // And null-terminate.
    Lcd_Out (2, 2, disp);                      // Display it then wait.
    Delay_ms (50);
}

换另一种方式,只需使用:

for (i = STR_SZ; i >= 0; i--) {
    // blah blah blah
}

如果您正在寻找更完整的示例,请尝试:

#define STR_SZ 14
// PreCond: from and to MUST be 14-character strings. EXACTLY!
// Pass in from and to strings and 1 to go left, 0 to go right.

void transition (char *from, char *to, int goLeft) {
    // Space for transition and display strings.
    char str[STR_SZ * 2 + 1];
    char disp[STR_SZ + 1];

    // Transition variables.
    int pos, start, end, incr;

    // Check preconditions.
    if (strlen (from) != STR_SZ) return;
    if (strlen (to) != STR_SZ) return;

    // Different values for each direction.
    if (goLeft) {
        start = 0; end = STR_SZ + 1; incr = 1;
        strcpy (str, from); strcat (str, to);
    } else {
        start = STR_SZ; end = -1; incr = -1;
        strcpy (str, to); strcat (str, from);
    }

    // Do the transitions.
    for (pos = start; pos != end; pos += incr) {
        // Copy string portion to display then delay.
        memcpy (disp, &(str[i]), STR_SZ);
        disp[STR_SZ] = '\0';
        Lcd_Out (2, 2, disp);
        Delay_ms (50);
    }
}

这是未经测试的(除了在我脑海中,这通常是相当不错的)所以你应该把它视为一个起点.