diff --git a/mindspore/ccsrc/dataset/engine/datasetops/source/celeba_op.cc b/mindspore/ccsrc/dataset/engine/datasetops/source/celeba_op.cc
index f016481af6..4849eeac63 100644
--- a/mindspore/ccsrc/dataset/engine/datasetops/source/celeba_op.cc
+++ b/mindspore/ccsrc/dataset/engine/datasetops/source/celeba_op.cc
@@ -38,8 +38,8 @@ Status CelebAOp::Builder::Build(std::shared_ptr<CelebAOp> *op) {
   MS_LOG(DEBUG) << "Celeba dataset type is " << builder_dataset_type_.c_str() << ".";
   RETURN_IF_NOT_OK(SanityCheck());
   if (builder_sampler_ == nullptr) {
-    int64_t num_samples = 0;
-    int64_t start_index = 0;
+    const int64_t num_samples = 0;
+    const int64_t start_index = 0;
     builder_sampler_ = std::make_shared<SequentialSampler>(start_index, num_samples);
   }
 
diff --git a/mindspore/ccsrc/dataset/engine/datasetops/source/cifar_op.cc b/mindspore/ccsrc/dataset/engine/datasetops/source/cifar_op.cc
index 5867d5e7ea..e2ac8dd31e 100644
--- a/mindspore/ccsrc/dataset/engine/datasetops/source/cifar_op.cc
+++ b/mindspore/ccsrc/dataset/engine/datasetops/source/cifar_op.cc
@@ -46,8 +46,8 @@ CifarOp::Builder::Builder() : sampler_(nullptr) {
 Status CifarOp::Builder::Build(std::shared_ptr<CifarOp> *ptr) {
   RETURN_IF_NOT_OK(SanityCheck());
   if (sampler_ == nullptr) {
-    int64_t num_samples = 0;
-    int64_t start_index = 0;
+    const int64_t num_samples = 0;
+    const int64_t start_index = 0;
     sampler_ = std::make_shared<SequentialSampler>(start_index, num_samples);
   }
   schema_ = std::make_unique<DataSchema>();
@@ -430,7 +430,11 @@ Status CifarOp::CountTotalRows(const std::string &dir, bool isCIFAR10, int64_t *
         std::string err_msg = "Invalid cifar100 file path";
         RETURN_STATUS_UNEXPECTED(err_msg);
       }
-      std::string file_name(file.substr(pos + 1));
+      std::string file_name;
+      if (file.size() > 0)
+        file_name = file.substr(pos + 1);
+      else
+        RETURN_STATUS_UNEXPECTED("Invalid string length!");
       if (file_name.find("test") != std::string::npos) {
         num_cifar100_records = 10000;
       } else if (file_name.find("train") != std::string::npos) {
diff --git a/mindspore/ccsrc/dataset/engine/datasetops/source/image_folder_op.cc b/mindspore/ccsrc/dataset/engine/datasetops/source/image_folder_op.cc
index bc5caf3b7e..7ffb63a6ba 100644
--- a/mindspore/ccsrc/dataset/engine/datasetops/source/image_folder_op.cc
+++ b/mindspore/ccsrc/dataset/engine/datasetops/source/image_folder_op.cc
@@ -36,8 +36,8 @@ ImageFolderOp::Builder::Builder() : builder_decode_(false), builder_recursive_(f
 Status ImageFolderOp::Builder::Build(std::shared_ptr<ImageFolderOp> *ptr) {
   RETURN_IF_NOT_OK(SanityCheck());
   if (builder_sampler_ == nullptr) {
-    int64_t num_samples = 0;  // default num samples of 0 means to sample entire set of data
-    int64_t start_index = 0;
+    const int64_t num_samples = 0;  // default num samples of 0 means to sample entire set of data
+    const int64_t start_index = 0;
     builder_sampler_ = std::make_shared<SequentialSampler>(start_index, num_samples);
   }
   builder_schema_ = std::make_unique<DataSchema>();
diff --git a/mindspore/ccsrc/dataset/engine/datasetops/source/manifest_op.cc b/mindspore/ccsrc/dataset/engine/datasetops/source/manifest_op.cc
index 70867ed290..8b22f9dcfa 100644
--- a/mindspore/ccsrc/dataset/engine/datasetops/source/manifest_op.cc
+++ b/mindspore/ccsrc/dataset/engine/datasetops/source/manifest_op.cc
@@ -39,8 +39,8 @@ ManifestOp::Builder::Builder() : builder_sampler_(nullptr), builder_decode_(fals
 Status ManifestOp::Builder::Build(std::shared_ptr<ManifestOp> *ptr) {
   RETURN_IF_NOT_OK(SanityCheck());
   if (builder_sampler_ == nullptr) {
-    int64_t num_samples = 0;
-    int64_t start_index = 0;
+    const int64_t num_samples = 0;
+    const int64_t start_index = 0;
     builder_sampler_ = std::make_shared<SequentialSampler>(start_index, num_samples);
   }
   builder_schema_ = std::make_unique<DataSchema>();
diff --git a/mindspore/ccsrc/dataset/engine/datasetops/source/mindrecord_op.cc b/mindspore/ccsrc/dataset/engine/datasetops/source/mindrecord_op.cc
index c89d6cba3d..e461c2988f 100644
--- a/mindspore/ccsrc/dataset/engine/datasetops/source/mindrecord_op.cc
+++ b/mindspore/ccsrc/dataset/engine/datasetops/source/mindrecord_op.cc
@@ -124,6 +124,7 @@ MindRecordOp::MindRecordOp(int32_t num_mind_record_workers, int32_t rows_per_buf
       operators_(operators),
       num_mind_record_workers_(num_mind_record_workers),
       block_reader_(block_reader),
+      num_rows_(0),
       buffers_needed_(0),
       buf_cnt_(0),
       ended_worker_(0),
diff --git a/mindspore/ccsrc/dataset/engine/datasetops/source/mnist_op.cc b/mindspore/ccsrc/dataset/engine/datasetops/source/mnist_op.cc
index 4ecc1e96ee..07726f5033 100644
--- a/mindspore/ccsrc/dataset/engine/datasetops/source/mnist_op.cc
+++ b/mindspore/ccsrc/dataset/engine/datasetops/source/mnist_op.cc
@@ -41,8 +41,8 @@ MnistOp::Builder::Builder() : builder_sampler_(nullptr) {
 Status MnistOp::Builder::Build(std::shared_ptr<MnistOp> *ptr) {
   RETURN_IF_NOT_OK(SanityCheck());
   if (builder_sampler_ == nullptr) {
-    int64_t num_samples = 0;
-    int64_t start_index = 0;
+    const int64_t num_samples = 0;
+    const int64_t start_index = 0;
     builder_sampler_ = std::make_shared<SequentialSampler>(start_index, num_samples);
   }
   builder_schema_ = std::make_unique<DataSchema>();
diff --git a/mindspore/ccsrc/dataset/engine/datasetops/source/voc_op.cc b/mindspore/ccsrc/dataset/engine/datasetops/source/voc_op.cc
index 2cbb1756b9..35d4475710 100644
--- a/mindspore/ccsrc/dataset/engine/datasetops/source/voc_op.cc
+++ b/mindspore/ccsrc/dataset/engine/datasetops/source/voc_op.cc
@@ -55,8 +55,8 @@ VOCOp::Builder::Builder() : builder_decode_(false), builder_sampler_(nullptr) {
 Status VOCOp::Builder::Build(std::shared_ptr<VOCOp> *ptr) {
   RETURN_IF_NOT_OK(SanityCheck());
   if (builder_sampler_ == nullptr) {
-    int64_t num_samples = 0;
-    int64_t start_index = 0;
+    const int64_t num_samples = 0;
+    const int64_t start_index = 0;
     builder_sampler_ = std::make_shared<SequentialSampler>(start_index, num_samples);
   }
   builder_schema_ = std::make_unique<DataSchema>();
diff --git a/mindspore/ccsrc/dataset/text/kernels/ngram_op.cc b/mindspore/ccsrc/dataset/text/kernels/ngram_op.cc
index f72e2f35a0..dcac9b0285 100644
--- a/mindspore/ccsrc/dataset/text/kernels/ngram_op.cc
+++ b/mindspore/ccsrc/dataset/text/kernels/ngram_op.cc
@@ -59,6 +59,8 @@ Status NgramOp::Compute(const std::shared_ptr<Tensor> &input, std::shared_ptr<Te
     if (end_ind - start_ind < n) {
       res.emplace_back(std::string());  // push back empty string
     } else {
+      if (end_ind - n < 0) RETURN_STATUS_UNEXPECTED("loop condition error!");
+
       for (int i = start_ind; i < end_ind - n; i++) {
         res.emplace_back(str_buffer.substr(offsets[i], offsets[i + n] - offsets[i] - separator_.size()));
       }