(window.webpackJsonp=window.webpackJsonp||[]).push([[878],{1286:function(t,s,a){"use strict";a.r(s);var n=a(31),e=Object(n.a)({},(function(){var t=this,s=t.$createElement,a=t._self._c||s;return a("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[a("h1",{attrs:{id:"pointers-unsafe-code"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#pointers-unsafe-code"}},[t._v("#")]),t._v(" Pointers & Unsafe Code")]),t._v(" "),a("h2",{attrs:{id:"introduction-to-unsafe-code"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#introduction-to-unsafe-code"}},[t._v("#")]),t._v(" Introduction to unsafe code")]),t._v(" "),a("p",[t._v("C# allows using pointer variables in a function of code block when it is marked by the "),a("code",[t._v("unsafe")]),t._v(" modifier. The unsafe code or the unmanaged code is a code block that uses a pointer variable.")]),t._v(" "),a("p",[t._v("A pointer is a variable whose value is the address of another variable i.e., the direct address of the memory location. similar to any variable or constant, you must declare a pointer before you can use it to store any variable address.")]),t._v(" "),a("p",[t._v("The general form of a pointer declaration is:")]),t._v(" "),a("div",{staticClass:"language-cs extra-class"},[a("pre",{pre:!0,attrs:{class:"language-cs"}},[a("code",[t._v("type "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("*")]),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("var")]),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("-")]),t._v("name"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n\n")])])]),a("p",[t._v("Following are valid pointer declarations:")]),t._v(" "),a("div",{staticClass:"language-cs 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"),a("span",{pre:!0,attrs:{class:"token number"}},[t._v("31627176")]),t._v("\nValue of list"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("[")]),a("span",{pre:!0,attrs:{class:"token number"}},[t._v("2")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("]")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("=")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token number"}},[t._v("200")]),t._v("\n\n")])])]),a("h2",{attrs:{id:"compiling-unsafe-code"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#compiling-unsafe-code"}},[t._v("#")]),t._v(" Compiling Unsafe Code")]),t._v(" "),a("p",[t._v("For compiling unsafe code, you have to specify the "),a("code",[t._v("/unsafe")]),t._v(" command-line switch with command-line compiler.")]),t._v(" "),a("p",[t._v("For example, to compile a program named prog1.cs containing unsafe code, from command line, give the command:")]),t._v(" "),a("div",{staticClass:"language-cs extra-class"},[a("pre",{pre:!0,attrs:{class:"language-cs"}},[a("code",[t._v("csc "),a("span",{pre:!0,attrs:{class:"token operator"}},[t._v("/")]),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("unsafe")]),t._v(" prog1"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(".")]),t._v("cs\n\n")])])]),a("p",[t._v("If you are using Visual Studio IDE then you need to enable use of unsafe code in the project properties.")]),t._v(" "),a("p",[a("a",{attrs:{href:"https://i.stack.imgur.com/2aPFY.png",target:"_blank",rel:"noopener noreferrer"}},[a("img",{attrs:{src:"https://i.stack.imgur.com/2aPFY.png",alt:"enter image description here"}}),a("OutboundLink")],1)]),t._v(" "),a("p",[t._v("To do this:")]),t._v(" "),a("li",[t._v("Open project properties by double clicking the properties node in the\nSolution Explorer.")]),t._v("\n- Click on the Build tab.\n"),a("li",[t._v('Select the option "Allow\nunsafe code"')]),t._v(" "),a("h2",{attrs:{id:"retrieving-the-data-value-using-a-pointer"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#retrieving-the-data-value-using-a-pointer"}},[t._v("#")]),t._v(" Retrieving the Data Value Using a Pointer")]),t._v(" "),a("p",[t._v("You can retrieve the data stored at the located referenced by the pointer variable, using the ToString() method. The following example demonstrates this:")]),t._v(" "),a("div",{staticClass:"language-cs extra-class"},[a("pre",{pre:!0,attrs:{class:"language-cs"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("using")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token namespace"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("namespace")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token namespace"}},[t._v("UnsafeCodeApplication")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("Program")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token 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"),a("span",{pre:!0,attrs:{class:"token number"}},[t._v("20")]),t._v("\nAddress "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("is")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(":")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token number"}},[t._v("77128984")]),t._v("\n\n")])])]),a("h2",{attrs:{id:"passing-pointers-as-parameters-to-methods"}},[a("a",{staticClass:"header-anchor",attrs:{href:"#passing-pointers-as-parameters-to-methods"}},[t._v("#")]),t._v(" Passing Pointers as Parameters to Methods")]),t._v(" "),a("p",[t._v("You can pass a pointer variable to a method as parameter. The following example illustrates this:")]),t._v(" "),a("div",{staticClass:"language-cs extra-class"},[a("pre",{pre:!0,attrs:{class:"language-cs"}},[a("code",[a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("using")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token namespace"}},[t._v("System")]),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v(";")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("namespace")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token namespace"}},[t._v("UnsafeCodeApplication")]),t._v("\n"),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("class")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token class-name"}},[t._v("TestPointer")]),t._v("\n   "),a("span",{pre:!0,attrs:{class:"token punctuation"}},[t._v("{")]),t._v("\n      "),a("span",{pre:!0,attrs:{class:"token keyword"}},[t._v("public")]),t._v(" "),a("span",{pre:!0,attrs:{class:"token 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