The technical deduction of function parameter degradation as pointer in C language array

//the technical deduction of the function parameter degradation of the array as a pointer#include <stdio.h>#include<stdlib.h>#include<string.h>//a technique deduction of function parameter degradation as pointer in one-dimensional arrayvoidPRINTFA (Char* strarr[3]);//in computers, arrays are stored linearly, and two-dimensional array elements are arranged in a//For example: 1,2,3,4,5,6,7,8,9 like this set of data we can think of as a one-dimensional array int a[9]={1,2,3,4,5,6,7,8,9};//It can also be considered a two-dimensional array int b[3][3]={1,2,3,4,5,6,7,8,9};//so the computer doesn't know what the step size of the array name is, how many bytes a+1 move or how many bytes the b+1 moves.//This requires the programmer to tell the computer what the step size of the array name is.//for the subject void PRINTFA (char * strarr[3]); Array to do function parameters The array is a one-dimensional array array element type is char *//then the size of the array strarr should be sizeof (char *) or 4 bytes//so we just have to tell the computer that you jump 4 bytes and it's OK.//so technical deduction for PRINTFBvoidPRINTFB (Char*strarr[]);//because the computer doesn't care how many of your elements are 3 or 30 and the computer doesn't matter what the programmer needs to be concerned about (this is the array cross-border problem)//function Parameter char * strarr[] also tell the computer I am a one-dimensional array array element is a char * type//so the size of the array strarr is either sizeof (char *) or 4 bytes//then we continue to deduce that since the computer only needs to determine the step size of each move of the array is 4 bytes .//then void printfc (char * * strarr); it is also possible to write Strarr is a pointer to a variable in the Strarr of a type that is char *//The step is only related to the value of the pointer, so the Strarr step is sizeof (char *) or 4 bytes//so the C language developer has done the optimization printfc (and I have no problem designing C language is so optimized)voidPRINTFC (Char**Strarr);//char * strarr[3] has 2 benefits for parameter degradation to char * * Strarr)//Benefit 1: Copying a one-dimensional array char * strarr[3] than copying a pointer char * * Strarr will consume more memory space//char * strarr[3] requires sizeof (char *) * 3 = 12 bytes of memory space;//while char * * * * * * Strarr requires sizeof (char * *) = 4 bytes of memory space;//savings in memory and resource consumption when creating arrays//Benefit 2: Reduced useless parsing, 3 useless for char * strarr[3] elements//This is a one-dimensional array this information is useless, because when traversing the array from the beginning of the first address to traverse, just give the computer a first address on the line//the computer traverses backwards from the first address without knowing what he is, just know how much each step is .//the technical deduction of the function parameter degradation as a pointer in a two-dimensional arrayvoidPRINTFD (intarr[3][4]);//for a two-dimensional array, the computer also needs to know the array name Arr's step is the number of bytes to be moved every time the computer is traversed.//so first we should determine the array name what type of arr is//The array name is a pointer to the first element of the array (my own inference) then the two-dimensional array can be imagined as a one-dimensional array, except that each element of this one-dimensional array is special, or a one-dimensional array//so according to the inferred array name, the type of arr is a one-dimensional array of pointers to a one-dimensional array that defines typedef int MYARR[4];//The definition of a one-dimensional array pointer is such a typedef int (* Pmyarr) [4];//a one-dimensional array pointer defines a simplified version of the INT (* Pmyarr) that is so defined [4];//so the type of the array name arr is int (* Pmyarr) [4]; However, the step size of the array name arr needs to be determined based on the value of the array name arr.//The value of the array name arr is the first address of a one-dimensional array type that is typedef int MYARR[4], and the size of typedef int MYARR[4] is sizeof (int) *4=20 bytes//the step size for the array name arr is 20 bytes//The deduction of a one-dimensional array indicates that an array element is not important to a computer two-bit array elements can be thought of as one-dimensional arrays//Push performance void printfd (int arr[][4]);voidPRINTFE (intarr[][4]);//and because the computer only needs to know the first address and the stride size, can use INT (*p) [4] instead of int arr[][4]voidPRINTFF (int(*arr) [4]);//combined with the above analysis, we deduced that the function parameter of the array is degenerate into a pointer, and the type of the pointer is the type of the array name voidMain () {Char* strarr[3] = {"123","456","789"}; intarr[3][4] = {0 }; System ("Pause");}

The technical deduction of function parameter degradation as pointer in C language array