int转ascii

void itoa(long int value, char* string) {
	int mod,count=0;
	char temp[64];

	if (value == 0) {
		*string = '0';
		*(string + 1) = '';
	}
	else {
		while (value != 0) {   //从低位到高位分解出各个字符
			mod = value % 10;
			cout << (char)(mod + 48) << endl;
			value = (int)(value / 10);
			temp[count] = (char)(mod + 48); //'0'-'9': 48-57
			count++;
		}
		for (int i = count - 1; i >= 0; i--) {  // 倒序输出
			*string++ = temp[i];
		}
		*string = '';
	}
}

int main(void) {
	char string[64];
	itoa(123456,string);	
	cout << string << endl;
	system("pause");
	return 0;
}

上述程序输出：
6
5
4
3
2
1
123456

无符号数和有符号数相加

int main(void) {
	unsigned char a = -1;
	char b = 44;
	int c;
	printf("0x%x
", a);
	printf("0x%x
", b);
	printf("0x%x
", a + b);
	c = a + b;
	cout << c << endl;
	system("pause");
	return 0;
}

以上程序段输出：
0xff
0x2c
0x12b
299

解释：a = -1 = 8'b1111_1111, b = 44 = 8'b0010_1100, a+b = 1_0010_1011=299

指针自加

int main(void) {
	int a[] = { 1,3,5,7,11,13,15,17,19 };
	int *p = a + 6;
	for (int i = 0; i < 5; i++)
	{
		switch (i)
		{
		case(4): {cout << (*--p); break; }
		case 3: {cout << (*p++); break; }
		case 2: {cout << (*p--); break;}
		case 1: {cout << (*++p); break; }
		default: p--;
			break;
		}

	}
	system("pause");
	return 0;
}

以上程序段输出：15151313

字符数组与字符数组的连接

void strcat(char s[], char ct[]) {
	int i=0, j=0;
	while (s[i] != '') i++;
	while (ct[j] != '') s[i++] = ct[j++];
	s[i] = '';
}

int main(void) {
	char a[40] = "wt ";
	char b[20] = "is a postgraduate";
	strcat(a, b);
	cout << "连接后的字符串为：" << endl;
	cout << a<<endl;
	system("pause");
	return 0;

字符数组的复制

void strcpy1(char s[], char ct[]) {
	int i = 0;
	while (ct[i]) {
		s[i] = ct[i];
		i++;
	}
	s[i] = '';
}

void strcpy2(char s[], char ct[]) {
	while (*ct) {
		*s++ = *ct++;
	}
	*s = '';
}

void strcpy3(char * s, char * ct) {
	while (*ct) {
		*s++ = *ct++;
	}
	*s = '';
}

指针与数组相关的运算

int main(void) {
	int i, fibon [10] = { 0,1,1,2,3,5,8,13,21,34 }, *pfib1, *pfib2; // fibon为指针常量，即隐含说明“int * const fibon”
	pfib1 = pfib2 = fibon;
	cout << "使用数组显示Fibonacci数列" << endl;
	for (i = 0; i < sizeof(fibon)/sizeof(*fibon); i++)  // sizeof函数返回的是总的存储，fibon一共10个整型元素，所有=40
		cout << fibon[i] << '	' << pfib1[i] <<endl;    // "[]"是以指针作为操作数的，fibon[i]被编译器解释为*(fibon+1)
	cout << "使用指针显示Fibonacci数列" << endl;
	for (i = 0; i < 10; i++)
		cout << *(fibon + i) << '	' << *pfib2++ << endl; // *pfib2++ 表示*(pfib2++)，先取值*pfib2，再将指针移到下一个元素

	system("pause");
	return 0;
}

使用数组显示Fibonacci数列
0       0
1       1
1       1
2       2
3       3
5       5
8       8
13      13
21      21
34      34
使用指针显示Fibonacci数列
0       0
1       1
1       1
2       2
3       3
5       5
8       8
13      13
21      21
34      34