# 编程实例
#### 实例描述
调用原子操作相关接口，观察结果：
1. 创建两个任务 
   1. 任务一用LOS_AtomicInc对全局变量加100次。
   
   2. 任务二用LOS_AtomicDec对全局变量减100次。
   
   
   
   
2. 子任务结束后在主任务中打印全局变量的值。
 
#### 编程示例
```
#include "los_hwi.h"
#include "los_atomic.h"
#include "los_task.h"
UINT32 g_testTaskId01;
UINT32 g_testTaskId02;
Atomic g_sum;
Atomic g_count;
UINT32 Example_Atomic01(VOID)
{
    int i = 0;
    for(i = 0; i < 100; ++i) {
        LOS_AtomicInc(&g_sum);
    }
    LOS_AtomicInc(&g_count);
    return LOS_OK;
}
UINT32 Example_Atomic02(VOID)
{
    int i = 0;
    for(i = 0; i < 100; ++i) {
        LOS_AtomicDec(&g_sum);
    }
    LOS_AtomicInc(&g_count);
    return LOS_OK;
}
UINT32 Example_TaskEntry(VOID)
{
    TSK_INIT_PARAM_S stTask1={0};
    stTask1.pfnTaskEntry = (TSK_ENTRY_FUNC)Example_Atomic01;
    stTask1.pcName       = "TestAtomicTsk1";
    stTask1.uwStackSize  = LOSCFG_BASE_CORE_TSK_DEFAULT_STACK_SIZE;
    stTask1.usTaskPrio   = 4;
    stTask1.uwResved     = LOS_TASK_STATUS_DETACHED;
    TSK_INIT_PARAM_S stTask2={0};
    stTask2.pfnTaskEntry = (TSK_ENTRY_FUNC)Example_Atomic02;
    stTask2.pcName       = "TestAtomicTsk2";
    stTask2.uwStackSize  = LOSCFG_BASE_CORE_TSK_DEFAULT_STACK_SIZE;
    stTask2.usTaskPrio   = 4;
    stTask2.uwResved     = LOS_TASK_STATUS_DETACHED;
    LOS_TaskLock();
    LOS_TaskCreate(&g_testTaskId01, &stTask1);
    LOS_TaskCreate(&g_testTaskId02, &stTask2);
    LOS_TaskUnlock();
    while(LOS_AtomicRead(&g_count) != 2);
    dprintf("g_sum = %d\n", g_sum);
    return LOS_OK;
}
```
#### 结果验证
```
g_sum = 0
```
#### 完整实例代码
[sample_atomic.c](https://support.huaweicloud.com/kernelmanual-LiteOS/resource/sample_atomic.c)