asm 서브루틴

section .data
text db "Hello, World!",10,0
text2 db "World?",10,0

Section .text
global _start

_start:
mov rax, text
call _print

mov rax, text2
call _print

mov rax, 60
mov rdi, 0
syscall

;input: rax as pointer to string
;output: print string at rax
_print:
push rax
mov rbx, 0
_printLoop:
inc rax
inc rbx
mov cl,  [rax]
cmp cl, 0
jne _printLoop

mov rax, 1
mov rdi, 1
pop rsi
mov rdx, rbx
syscall

ret

; nasm -f elf64 05_SubRoutine.asm -o 05_SubRoutine.o
; ld 05_SubRoutine.o -o 05_SubRoutine
; ./05_SubRoutine

구조체 malloc() 사용법.

#include <stdio.h>
#include <stdlib.h>

struct product{
float price;
char productName[30];
};

int main(void){
struct product *pProducts;

int i, j;

int numberOfProducts;
printf("Enter the Number of products to store: ");

scanf("%d", &numberOfProducts);
pProducts = (struct product *) malloc(numberOfProducts * sizeof(struct product));

for(i=0; i < numberOfProducts; ++i){
printf("Enter a Product Name: ");
scanf("%s", &(pProducts+i)->productName);

printf("Enter a Product Price: ");
scanf("%e", &(pProducts+i)->price);

}

printf("Products Stored\n");

for(j=0; j < numberOfProducts; ++j){
printf("%s\t%.2f\n", (pProducts+j)->productName, (pProducts+j)->price);
}

free(pProducts);

return 0;
}

/*
 * ./02_malloc_struct_store
Enter the Number of products to store: 3
Enter a Product Name: Egg
Enter a Product Price: .25
Enter a Product Name: Fish
Enter a Product Price: 11
Enter a Product Name: Bread
Enter a Product Price: 3
Products Stored
Egg 0.25
Fish 11.00
Bread 3.00 */

변수 malloc 사용법.

#include <stdio.h>
#include <stdlib.h>

int main(void){
int amtOfNumbersToStore;

printf("How many numbers do you want to store: ");

scanf("%d", &amtOfNumbersToStore);

int * pRandomNumbers;

pRandomNumbers = (int *) malloc(amtOfNumbersToStore * sizeof(int));

if(pRandomNumbers != NULL){
int i = 0;

printf("Enter a Number of Quit: ");

while(i < amtOfNumbersToStore && scanf("%d", &pRandomNumbers[i]) == 1) {

printf("Enter a number or Quit: ");
i++;
}
printf("\nYou entered the following numbers\n");

for(int j=0; j < i; j++){
printf("%d\n", pRandomNumbers[j]);
}
}

free(pRandomNumbers);

// 10k 더이상 사용되지 않지만 메모리 해제 안함
// 10k 더이상 사용되지 않지만 메모리 해제 안함
// 10k 더이상 사용되지 않지만 메모리 해제 안함

return 0;

}

/*
./01_number_store
How many numbers do you want to store: 10
Enter a Number of Quit: 1
Enter a number or Quit: 2
Enter a number or Quit: 3
Enter a number or Quit: 4
Enter a number or Quit: 5
Enter a number or Quit: q

You entered the following numbers
1
2
3
4
5
*/

문자 정보 확인

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

void noMoreNewline(char* theString){
char * isANewline;

isANewline = strrchr(theString, '\n');

// 개형문자
if(isANewline){
*isANewline = '\0';
}
}

void makeLowercase(char* theString){
int i = 0;

while(theString[i]){
// 소문자 변경
theString[i] = tolower(theString[i]);
// 대문자 변경
// theString[i] = toupper(theString[i]);
i++;
}
}

void getCharInfo(){
char theChar;

while((theChar = getchar()) != '\n'){
printf("Letter of Number %d\n\n", isalnum(theChar));

printf("Alphabetic Char %d\n\n", isalpha(theChar));

printf("Standard Blank %d\n\n", isblank(theChar));

printf("Ctrl Char %d\n\n", iscntrl(theChar));

printf("Number Char %d\n\n", isdigit(theChar));

printf("Anything But space %d\n\n", isgraph(theChar));

printf("Lowercase %d\n\n", islower(theChar));

printf("Uppercase %d\n\n", isupper(theChar));

printf("Punctuation %d\n\n", ispunct(theChar));

printf("Any Space %d\n\n", isspace(theChar));
}
}

int main(void){
getCharInfo();
}

개형문자, 대소문자

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

void noMoreNewline(char* theString){
char * isANewline;

isANewline = strrchr(theString, '\n');

// 개형문자
if(isANewline){
*isANewline = '\0';
}
}

void makeLowercase(char* theString){
int i = 0;

while(theString[i]){
// 소문자 변경
theString[i] = tolower(theString[i]);
// 대문자 변경
// theString[i] = toupper(theString[i]);
i++;
}
}

int main(void){
char doYouWantToQuit[10];

printf("Enter quit to quit: ");

fgets(doYouWantToQuit, 10, stdin);

noMoreNewline(doYouWantToQuit);

makeLowercase(doYouWantToQuit);

printf(doYouWantToQuit);

while(strcmp(doYouWantToQuit, "quit")){
printf("Enter quit to quit: ");
fgets(doYouWantToQuit, 10, stdin);
noMoreNewline(doYouWantToQuit);
makeLowercase(doYouWantToQuit);

}

printf("Thank you for typing quit %s\n\n", doYouWantToQuit);

}

개행 문자.

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

void noMoreNewline(char* theString){
char * isANewline;

isANewline = strrchr(theString, '\n');

if(isANewline){
*isANewline = '\0';
}
}
int main(void){
char doYouWantToQuit[10];

printf("Enter quit to quit: ");

fgets(doYouWantToQuit, 10, stdin);

noMoreNewline(doYouWantToQuit);

printf(doYouWantToQuit);
}

putchar() 사용 예

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

int main(void){
char * randomString = "Just some random stuff";

#if 0 // 간접 연산자 지정 접근
while(*randomString){
putchar(*randomString++);
}
#endif

int i = 0;

// 배열 접근
while(randomString[i] != '\0'){
putchar(randomString[i++]);
}
}

fgets(), fputs() 사용 예

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

int main(void){
char name[50];

printf("What is your name? ");

fgets(name, 50, stdin);

fputs("Hi ", stdout);
fputs(name, stdout);
}

gets(), puts() 사용 예.

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

int main(void){
char name[50];
printf("What is your name? ");
gets(name);
puts("Hi");
puts(name);
}

getchar() putchar() 사용 예

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

int main(void){
char theChar;

while((theChar = getchar()) != '~'){
putchar(theChar);
}
}

숫자의 합

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <ctype.h>

int main(void){

// bool isAnumber;
_Bool isANumber;

int number;
int sumOfNumbers = 0;

printf("Enter a Number: ");

isANumber = (scanf("%d", &number) == 1);

while(isANumber) {
sumO Numbers = sumOfNumbers + number;
printf("Enter a Number: ");
isANumber = (scanf("%d", &number) == 1);
}

printf("The Sum is %d\n\n", sumOfNumbers);
}