class function returning junk chars at end of string

I have some classes that i use to read the memory of a program. i made a function in that class to show the name of another class to shorten my code. Problem im having is that when i call my finction to print the text it has junk chars after it has got the right string, i have this working fine if i read the string outside of the class. i have tried both std::string and char*

class StringClass
{
public:
    char pad_0x0000[0x4];
    __int32 size;
    char String[150];

};//Size=0x003C

class CProgramName
{
public:
    char pad_0x0000[0x2C]; //0x0000
    DWORD Name; // StringClass

    std::string GetName()
    {
        if (!ISVALID(this->Name)) return "";
        StringClass ServerName = Read<StringClass>((DWORD)this->Name);

        return Name.String;
    }
};


printf_s("Name %s", ProgramName.GetName().c_str());