android 下 調用c語言時，常見數據類型強制轉換。

void TestMain()
{

    int i;
    char c;
    short s;
    float f;

    c = -1;
    f = (float)c;
    LOGE("1. c:0x%x\n", c);
    LOGE("1. f:%lf\n", f);
    c = 0;
    f = c;
    LOGE("2. c:0x%x\n", c);
    LOGE("2. f:%lf\n", f);
    c = -1;
    f = c;
    for (int i = 0; i < 1000; i++){
        f = f + c;
    }
    LOGI("3. f + c:%lf\n", f);
    i = -1;
    f = i;
    for (int idx = 0; idx < 1000; idx ++){
        f = f + i;
    }
    LOGI("3. f + i:%lf\n", f);
    
    c = 0;
    i = 1;
    f = (!c)*(i);
    for (int idx = 0; idx < 5; idx++){
        f = f + f;
    }
    LOGE("4. f:%lf\n", f);
    
    s = -1;
    f = s;
    LOGE("5. f:%lf\n", f);

}

===============android=====================

04-10 22:40:30.108 27946-27946/com.example.myapplication E/DYZ: 1. c:0xff
04-10 22:40:30.108 27946-27946/com.example.myapplication E/DYZ: 1. f:255.000000
04-10 22:40:30.108 27946-27946/com.example.myapplication E/DYZ: 2. c:0x0
04-10 22:40:30.109 27946-27946/com.example.myapplication E/DYZ: 2. f:0.000000
04-10 22:40:30.109 27946-27946/com.example.myapplication I/DYZ: 3. f + c:255255.000000
04-10 22:40:30.109 27946-27946/com.example.myapplication I/DYZ: 3. f + i:-1001.000000
04-10 22:40:30.109 27946-27946/com.example.myapplication E/DYZ: 4. f:32.000000
04-10 22:40:30.109 27946-27946/com.example.myapplication E/DYZ: 5. f:-1.000000

=================windows====================
1. c:0xffffffff
1. f:-1.000000
2. c:0x0
2. f:0.000000
3. f + c:-1001.000000
3. f + i:-1001.000000
4. f:32.000000
5. f:-1.000000