day-13 代码
2021/10/7 23:14:11
本文主要是介绍day-13 代码,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!
获取系统时间
int main() { time_t now; struct tm local; while (1) { time(&now); localtime_s(&local, &now); cout.fill('0'); cout << local.tm_hour << ":"; cout.fill('0'); cout << local.tm_min << ":"; cout.fill('0'); cout << local.tm_sec << '\r'; Sleep(1000); } return 0; }
指针和二维数组
int main() { int a[][3]{ {5, 1, 2}, {3, 4, 0}, {8, 9, 7} }; int sum = 0; int* p = &(a[0][0]); int nlen = sizeof(a[0]) / sizeof(int); cout << *a << ", p = " << p << ", p+1 = "<< *(p+1) << ", nlen = " << nlen << endl; int i, j, t; for (i = 0; i < 3; i++) { cout << "*(a+i): " << *(a + i) << ", &(a[i][0]/a[i]): " << &a[i] << endl; //*(a+i)是指第i行的地址 cout << "line: " << i << ", p[i]:" << p[i] << endl; p = a[i]; for (j = 0; j < 3; j++) { t = *(p + j);// a[i][j]; //t = *(p++); sum += t; cout << "t=" << t << ", &t: " << &t << ", &a[i][j]: " << &a[i][j] << endl; } cout << endl; } cout << sum << endl; cout << endl; return 0; } /*错误 int main() { int a[][3]{ {5, 1, 2}, {3, 4, 0} }; int sum = 0; int* p = a[0]; cout << *a << " " << p << endl; int i, j, t; for (i = 0; i < 2; i++) { cout << "line: " << i << ", p[i]:" << p[i] << endl; for (j = 0; j < 3; j++) { //t = *(p + i) + j; a[i][j]; t = *(p++); sum += t; cout << "t=" << t << ", &t: " << &t << ", &a[i][j]: " << &a[i][j] << endl; } cout << endl; } cout << sum << endl; cout << endl; return 0; }*/
二维字符串指针数组
int main() { const char* ch[] = { "china", "c", "string" }; const char** p = ch; cout << **p << " " << **(p + 1) << " " << **(p + 2) << endl; cout << *p << " " << *(p + 1) << " " << *(p + 2) << endl; cout << endl; return 0; } /*output c c s china c string */
字符串数组和指针赋值
int main() { char ch1[] = { 'h', 'e', 'l', 'l', 'o' }; char ch2[] = "hello"; char* pch1 = ch1; //strcpy_s(pch1, ch1); char* pch2 = ch2; cout << "sizeof(ch1):" << sizeof(ch1) << ",ch1:" << ch1 << endl; cout << "sizeof(ch2):" << sizeof(ch2) << ",ch2:" << ch2 << endl; cout << "sizeof(pch1):" << sizeof(pch1) << ",pch1:" << pch1 << endl; cout << "sizeof(pch2):" << sizeof(pch2) << ",pch2:" << pch2 << endl; cout << endl; return 0; } /*output sizeof(ch1):5,ch1:hello烫烫烫炭g{婶 sizeof(ch2):6,ch2:hello sizeof(pch1):4,pch1:hello烫烫烫炭g{婶 sizeof(pch2):4,pch2:hello */
字符串指针数组
int main() { char ch1[] = { 'h', 'e', 'l', 'l', 'o' }; char ch2[] = "hello"; char* pch1 = ch1; *(pch1 + 5) = '\0'; //strcpy_s(pch1, ch1); char* pch2 = ch2; cout << "sizeof(ch1):" << sizeof(ch1) << ",ch1:" << ch1 << endl; cout << "sizeof(ch2):" << sizeof(ch2) << ",ch2:" << ch2 << endl; cout << "sizeof(pch1):" << sizeof(pch1) << ",pch1:" << pch1 << endl; cout << "sizeof(pch2):" << sizeof(pch2) << ",pch2:" << pch2 << endl; cout << endl; return 0; } /*output //报错 sizeof(ch1):5,ch1:hello sizeof(ch2):6,ch2:hello sizeof(pch1):4,pch1:hello sizeof(pch2):4,pch2:hello */
字符串常量指针
int main() { char ch1[] = "hello"; char* pch1 = ch1; const char* pch2 = "hello"; //phc2和pch3都指向常量存储区的同一个地址 const char* pch3 = "hello"; cout << (pch2 - pch3) << endl; cout << endl; return 0; } /*output 0 */
两次循环输出字符串指针数组
int main() { const char* point[] = { "one", "two", "string" }; int i = 0; while (*point[2]!='\0') { i++; cout << *point[2]++ << " "; cout << i << endl; } /*while (*point[2] != '\0') //此时*point[2]为空,不执行 { i++; cout << *point[2]++ << " "; cout << i << endl; }*/ while (*point[2] == '\0') { i++; cout << *point[2]++ << " "; cout << i << endl; } cout << endl; return 0; } /* s 1 t 2 r 3 i 4 n 5 g 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 */
拷贝char to char*
int main() { char arr[] = "there is a string"; char* point; char arr2[30] = ""; int i = 0, arrLen = 0; point = arr2; while (arr[arrLen]!='\0') { arrLen++; } for (i; i < arrLen; i++) { *point = arr[i]; cout << *point; point++; /**point++ = arr[i]; cout << *point;*/ } cout << endl; cout << arr2 << endl; cout << endl; return 0; } /*output there is a string there is a string /* there is a string */
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