C Language

Ladder Language (LD):PLC

Visual Studio ShortCuts:

Ctrl + .
Ctrl + K , Ctrl + D
Ctrl + K , Ctrl + F
Alt + ⬆
Alt + ⬇
Ctrl + B : Build project
Ctrl + Shift + B : Build Solution
Ctrl + F5 : Execute
Ctrl +F7 : Compile

F9: Set/Remove toggle breakpoint
F5: Start Debugging
F10: Step over
F11: Step into
Shift + F11: Step Out.
Ctrl + Shift + F9: Enable/Disable All Breakpoints.
Ctrl + Alt + B: View All Breakpoints.


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <Windows.h>    beep()
#include <time.h>


Disable Error Setting:

Project -> properties -> Configuration Properties -> C/C++ ->Advanced ->Disable Specific Warnings -> edit ->error NO.

Building only one *.c file

*.c -> properties -> Configuration Properties -> General -> Excluded From Build



conditional operator

condition ? value_if_true : value_if_false;


int max = n1 > n2 ? n1 : n2;
pirntf("%d", n1 > n2 ? n1 - n2 : n2 - n1);





#include <stdio.h>

int main(void)
{
	printf("%d", 15 + 37);
	return 0;
	}


#include <stdio.h>

int main(void) {
	int a, b, c, d, e;
	scanf_s("%d", &a);
	scanf_s("%d", &b);
	scanf_s("%d", &c);
	scanf_s("%d", &d);

	e = (a < b) ?
		((a < c) ? a : c) : ((b < c) ? b : c);//biggest number
	e = (a < b) ?
		((a < c) ? ((a < d) ? a : d) : ((c < d) ? c : d)) :
		((b < c) ? ((b < d) ? b : d) : ((c < d) ? c : d));//smallest number
	e = a < b ? a < c ? a < d ? a : d : c < d ? c : d : b < c ? b < d ? b : d : c < d ? c : d;//smallest number

	e = (a < b) ? a : b;
	e = (e < c) ? e : c;
	e = (e < d) ? e : d;

	printf("%d", e);
	return 0;
}



a==b==c -> First evaluate a==b,then evaluate 1==c or 0==c



#include <stdio.h>
int main(void) {
	printf("%c %d %d %d", 'A', 'A',sizeof('A'),sizeof("AA"));
	return 0;
}
-----------------------------------
result : A 65 4 3



character set :

#include <stdio.h>

int main() {
    char str[100];
    
    printf("Enter a line: ");
    scanf("%[^\n]", str);  // "Match all strings, excluding newline characters (\n)."

    printf("You entered: %s\n", str);
    return 0;
}


01/10/25 chap04 while

printf("%d",i--);//printf i first , then --
printf("%d",--i);//-- first , then printf i


01/24/25

'\0' == NULL
'A' == 65 == 0x41
printf("%c\n", '\x24');


void str_dcount(const char s[],int cnt[]) {
	int i = 0;
	while (s[i])
	{
		if (s[i] >= '0' && s[i <= '9']) {
			cnt[s[i] - '0']++;
			//s[i] >= 0x30 && s[i] <= 0x39;
			//s[i] >= 48 && s[i] < 57;
			//cnt[s[i] - 0x30]++;
			//cnt[s[i] - 48]++;

		}
		i++;
	}


printf("%c\n", '\x24');


if (s[i++] == c)


char* mymalloc() {
	char* pstr = (char*)malloc(6 * sizeof(char));
	if (pstr == NULL)
	{
		printf("failed");
		return NULL;
	}
	return pstr;
}


int str_len(const char* str) {
	int len = 0;
	while (str[len]!=NULL)
	{
		len++;
	}
	return len;
}

01/28/25

void set_idx(int* v, int n) {
	for (int i = 0; i < n; i++,v++)
		*v= i;
	// 1:for (int i = 0; i < n; i++)v[i] = i;
	/* 2:
	int i = 0;
	while (i < n){*v++ = i++;}
	*/
}


        fp1 = fopen("test1.txt", "r");
	fp2 = fopen("test2.txt", "w");
	if (fp1 == NULL)
	{
		printf("1 open failed!\n");
		return -1;
	}
	if (fp2 == NULL)
	{
		printf("2 open failed!\n");
		return -2;
	}
	while (fscanf(fp1, "%d%s%d", &no, name, &age) == 3)
	{
		printf("NO.=%d name=%s age=%d\n", no, name, age);
		fprintf(fp2, "%d,%s,%d\n", no,name,age);
	}
	fclose(fp1);
	fclose(fp2);



        unsigned long long date = 0x123456789ABCDEF0ULL;
	unsigned long long* p1 = &date;
	unsigned long* p2 = (unsigned long*)&date;
	unsigned int* p3 = (unsigned int*)&date;
	unsigned short* p4 = (unsigned short*)&date;
	unsigned char* p5 = (unsigned char*)&date;
	printf("&date=0x%p, 0x%llx\n", &date, date);
	printf("p5=0x%p, 0x%hhx\n", p5, *p5);
	printf("p4=0x%p, 0x%hx\n", p4, *p4);
	printf("p3=0x%p, 0x%x\n", p3, *p3);
	printf("p2=0x%p, 0x%lx\n", p2, *p2);
	printf("p1=0x%p, 0x%llx\n", p1, *p1);