1.读取shp文件
void ExtracInfo::ReadShapeFile(){OGRRegisterAll();OGRDataSource *poDS;poDS = OGRSFDriverRegistrar::Open("F:/test.shp", FALSE);if (poDS == NULL){//printf("Open failed \n");}OGRLayer *poLayer;poLayer = poDS->GetLayerByName("test");int layercount = poDS->GetLayerCount();//printf("layer count is : %d\n", layercount);OGRFeature *poFeature;poLayer->ResetReading();while((poFeature = poLayer->GetNextFeature()) != NULL){//printf("hello!\n");//get fieldOGRFeatureDefn *poFDefn = poLayer->GetLayerDefn();int iField;int fieldcount = poFDefn->GetFieldCount();//printf("Field count is : %d\n", poFDefn->GetFieldCount());int fieldv1;double fieldv2;string feildv3;for (iField = 0; iField < poFDefn->GetFieldCount(); iField ++){OGRFieldDefn * poFieldDefn = poFDefn->GetFieldDefn(iField);if (poFieldDefn->GetType() == OFTInteger){fieldv1 = poFeature->GetFieldAsInteger(iField);//printf("%d ", poFeature->GetFieldAsInteger(iField));}else if (poFieldDefn->GetType() == OFTReal){fieldv2 = poFeature->GetFieldAsDouble(iField);//printf("%3f ", poFeature->GetFieldAsDouble(iField));}else if (poFieldDefn->GetType() == OFTString){feildv3 = poFeature->GetFieldAsString(iField);//printf("%s ", poFeature->GetFieldAsString(iField));}//else//printf("%s", poFeature->GetFieldAsString(iField));}//以上操作与gdal官网一样//get Geometry获取polygon的信息OGRGeometry *poGeometry;poGeometry = poFeature->GetGeometryRef();double x, y;double area;if (poGeometry != NULL && wkbFlatten(poGeometry->getGeometryType()) == wkbPolygon){OGRPolygon *poPolygon = (OGRPolygon * )poGeometry;area = poPolygon->get_Area();OGRPoint point;OGRLinearRing *pOGRLinearRing = poPolygon->getExteriorRing();pOGRLinearRing->getPoint(0,&point);//得到第一个点的坐标x = point.getX();y = point.getY();//printf("%.6f, %.6f\n", poPoint->getX(), poPoint->getY());}else//printf("no point geometry\n");OGRFeature::DestroyFeature(poFeature);}OGRDataSource::DestroyDataSource(poDS);}2.shp文件添加字段
有时需要对已经存在的shp文件进行添加字段操作。代码如下：
OGRDataSource *poDS;poDS = OGRSFDriverRegistrar::Open("F:/test.shp", TRUE);//第二个参数表示只读还是可读写if (poDS == NULL){//printf("Open failed \n");}OGRLayer *poLayer;poLayer = poDS->GetLayerByName("test");int layercount = poDS->GetLayerCount();OGRFieldDefn poField("NewField", OFTReal);//poField.SetWidth(1); //设置的是格式化输出时的位数poField.SetPrecision(8);//设置精度，除了real类型，，其他的一般为0if (poLayer->CreateField(&poField) != OGRERR_NONE){// printf("Creating Name Field Failed\n");// exit(1);}OGRFeature *poFeature; poLayer->ResetReading();//设置从第0个要素开始读int featureNum = 0;while((poFeature = poLayer->GetNextFeature()) != NULL){OGRFeatureDefn *poFDefn = poLayer->GetLayerDefn();int fieldcount = poFDefn->GetFieldCount();poFeature->SetField(fieldcount – 1, featureNum);poLayer->SetFeature(poFeature);OGRFeature::DestroyFeature(poFeature);featureNum ++;}OGRDataSource::DestroyDataSource(poDS);刚开始老是添加不成功，最后发现是open函数里第二个参数，如果默认设置为FALSE，则表示只读；需要把它设置为TRUE才可读写。
3.创建shp文件
下面主要说说创建多边形shp文件。创建的方法：使用的WKT格式的字符串来进行创建。也可以使用其他的方式进行创建（参考大神博客：点击打开链接）。但是它是wkt方法的C#、python代码，c++代码对应的函数没查到。所以用另一种方法创建如下：
const char *pszDriverName = "ESRI Shapefile";OGRSFDriver *poDriver;OGRRegisterAll();poDriver = OGRSFDriverRegistrar::GetRegistrar()->GetDriverByName(pszDriverName);if (poDriver == NULL){//printf("%s driver not available \n", pszDriverName);}OGRDataSource *poDS;poDS = poDriver->CreateDataSource("F:/zjq/testProject/ogrtest/polygon.shp", NULL);if (poDS == NULL){// printf("Create shapefile failed\n");// exit(1);}OGRLayer *poLayer;poLayer = poDS->CreateLayer("polygon1", NULL, wkbPolygon, NULL);if (poLayer == NULL){// printf("Layer create failed\n");// exit(1);}//下面创建属性表OGRFieldDefn poFieldID("ID", OFTInteger);//创建ID字段poLayer->CreateField(&poFieldID);OGRFieldDefn poFieldname("Name", OFTString);//创建Name字段poFieldname.SetWidth(32);poLayer->CreateField(&poFieldname);double x = 0.0, y = 0.0;for (int i = 0; i < 10; i++){string szname = "a_" + QString::number(i).toStdString();OGRFeature *poFeature;poFeature = OGRFeature::CreateFeature( poLayer->GetLayerDefn() );poFeature->SetField(0, i);poFeature->SetField(1, szname.c_str());OGRLinearRing ring;ring.addPoint(0 + 10 * i, 0 + 10 *i);ring.addPoint(0 +10 * i, 10 + 10 *i);ring.addPoint(10 + 10 *i, 10 + 10 *i);ring.addPoint(10 + 10 *i, 0 + 10*i);ring.closeRings();//首尾点重合形成闭合环OGRPolygon polygon;polygon.addRing(&ring);poFeature->SetGeometry(&polygon);if ( poLayer->CreateFeature( poFeature) != OGRERR_NONE){// printf("Failed to create feature in shapefile \n");// exit(1);}OGRFeature::DestroyFeature(poFeature);}OGRDataSource::DestroyDataSource(poDS);以上创建代码的结果如下图所示：（QGIS显示）每个人在他的人生发轫之初，总有一段时光，
