diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4abed42d1e66b35d091d186f21a5c7351b1184a7..f7544c8297f5e1c9555389f93838f8a6e3dc5da2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 ## 2.0.2
 
-- ArkTs语法规则整改
+- ArkTs新语法适配
 - 解决发送多次请求，回调结果相互影响的问题
 
 ## 2.0.1
diff --git a/README.md b/README.md
index 6d38fdf3728ab0326eb9c6c0b7fd3c0f8ff2c397..eeb399815c3fb723a004abafb65590572fff56dc 100644
--- a/README.md
+++ b/README.md
@@ -42,6 +42,7 @@ For details about the environment configuration, see [Installing the OpenHarmony
 // Enable the native log feature.
 CoapClient.setNativeLogOpen(true);
 // Initiate a CoAP GET request. Replace this.coapUri with the actual URL.
+// Each coapClient corresponds to a COAP request task and cannot be reused.
 let coapClient = new CoapClient();
 let coapGet = coapClient.request(this.coapUri, CoapRequestMethod.GET, CoapRequestType.COAP_MESSAGE_CON);
 console.log("libcoap get test");
@@ -69,6 +70,7 @@ coapClient.setFormat(ContentFormat.PLAIN);
 // Set the data to be transparently transmitted.
 coapClient.setPayload("this is put test payload");
 // Initiate a CoAP PUT request. Replace this.coapUri with the actual URL.
+// Each coapClient corresponds to a COAP request task and cannot be reused.
 let coapPut = coapClient.request(this.coapUri, CoapRequestMethod.PUT, CoapRequestType.COAP_MESSAGE_CON);
 console.log("libcoap put test");
 // Asynchronous callback of the CoAP GET request
diff --git a/README_zh.md b/README_zh.md
index 55ebda3b1f04a528da9502c1ed0f8dba49b5d9cc..4c9599a867ed9bace782814cd6f564e82db9b8d9 100644
--- a/README_zh.md
+++ b/README_zh.md
@@ -41,6 +41,7 @@ OpenHarmony ohpm
 // 打开native log开关
 CoapClient.setNativeLogOpen(true);
 // 发起coap get请求，注意this.coapUri请使用者换成真实的url
+// 每一个CoapClient对应一个COAP请求任务，不可复用
 let coapClient = new CoapClient();
 let coapGet = coapClient.request(this.coapUri, CoapRequestMethod.GET, CoapRequestType.COAP_MESSAGE_CON);
 console.log("libcoap get test");
@@ -68,6 +69,7 @@ coapClient.setFormat(ContentFormat.PLAIN);
 //设置透传数据
 coapClient.setPayload("this is put test payload");
 // 发起coap put请求，注意this.coapUri请使用者换成真实的url
+// 每一个CoapClient对应一个COAP请求任务，不可复用
 let coapPut = coapClient.request(this.coapUri, CoapRequestMethod.PUT, CoapRequestType.COAP_MESSAGE_CON);
 console.log("libcoap put test");
 //coap get请求异步回调
diff --git a/libcoap/src/main/cpp/coap-client.cpp b/libcoap/src/main/cpp/coap-client.cpp
index 6950baf5c933f91d164d011d543ef2d94fa0f1b7..19589f595e8b93fa997937a45a782607730dfaf0 100644
--- a/libcoap/src/main/cpp/coap-client.cpp
+++ b/libcoap/src/main/cpp/coap-client.cpp
@@ -854,7 +854,7 @@ std::string GenerateRandomString(int len)
     }
     char *str = new char[len];
     for (int i = 0; i < len; i++) {
-        int index = rand() % (sizeof charSet - 1);
+        int index = rand() % (charSet.length() - 1);
         str[i] = charSet[index];
     }
     std::string randomStr = str;