Sharepoint calculated field formula syntax - sharepoint

Question

I have to programmatically set the formula for a calculated field in a list.
This field has to be the sum of two other fields. Can you provide me with the syntax for the formula that I have to insert in the code? I cannot find any example.
Can you provide me also with a reference for formula syntax because I have also to create another calculated field which is the concatenation of two string fields.
Thank you

Answer 1

Calculated Field Formulas reference:
For your task use simply:
=[Column1] + [Column2]
Create Calculated field with server code reference
using (SPWeb oWebsite = SPContext.Current.Site.AllWebs["Website_Name"])
{
SPList oList = oWebsite.Lists["MyList"];
SPFieldCollection collFields = oList.Fields;
string strNewFieldName = collFields.Add("MyNewColumn",
SPFieldType.Calculated, false);
SPFieldCalculated strNewField =
(SPFieldCalculated)collFields[strNewFieldName];
strNewField.Formula = "=[Column1]<[Column2]";
strNewField.Update();
}
Create Calculated field with CSOM code reference1, reference2. As you see below you need to remeember about escape special characters in xml.
string formula = "<Formula>=FirstName& \" \" &LastName& \" (id: \" &EmployeeID& \" \"</Formula>"
+ "<FieldRefs>"
+ "<FieldRef Name='FirstName' />"
+ "<FieldRef Name='LastName' />"
+ "<FieldRef Name='EmployeeID' />"
+ "</FieldRefs>";
string schemaCalculatedField = "<Field ID='<GUID>' Type='Calculated' Name='FullName' StaticName='FullName'
DisplayName='Full Name' ResultType='Text' Required='TRUE' ReadOnly='TRUE'>" + formula + "</Field>";
Field fullNameField = demoList.Fields.AddFieldAsXml(schemaCalculatedField, true, AddFieldOptions.AddFieldInternalNameHint);
clientContext.ExecuteQuery();
Working code for your implementation (comments):
string formula = "<Formula>=Nome1&" "&Cognome1&"(id:"&Campo1&")"</Formula>" + "<FieldRefs>" + "<FieldRef Name='Nome1'/>" + "<FieldRef Name='Cognome1'/>" + "<FieldRef Name='Campo1'/>" + "</FieldRefs>";
string schemaCalculatedField = "<Field ID='1F2ABCC0-D243-40F0-A18D-E0AEF7FE3EB6' Type='Calculated' Name='FullName' StaticName='FullName' DisplayName='Full Name' ResultType='Text' Required='TRUE' ReadOnly='TRUE'>" + formula + "</Field>";
Field fullNameField = context.Web.Lists.GetByTitle("PnP Custom List3").Fields.AddFieldAsXml(schemaCalculatedField, true, AddFieldOptions.AddFieldInternalNameHint);
context.ExecuteQuery();