20.字元阵列
- 字元与字元阵列
- 一个字元型别变数可以储放一个字元 char ch = 'H';
- 一个字元阵列型别变数可以储放一到多个字元 如：char str [ ] = {'h', 'e', 'l', 'l', 'o',' '};
- 字串与字元阵列
- 字串是以 ' ' 表示结尾的字元阵列
- 字元阵列可以用 “字串内容” 进行初始化， 会自动加上 ' ' 字元 如：char str[] = ''Hello'';
1 #include <stdio.h> 2 3 void str_print(char str[]) 4 /* 5 { 6 int i; 7 for (i = 0; str[i] != ' '; i++) { 8 printf("%c", str[i]); 9 } 10 printf(" "); 11 } */ 12 13 { 14 printf("%s ", str); 15 } 16 int main() { 17 char str[] = "Hello world"; 18 str_print(str); 19 return 0; 20 } 21 22 23 Hello world 24 25 Process returned 0 (0x0) execution time : 11.821 s 26 Press any key to continue.
20.1 计算字串长度的练习
1 #include <stdio.h> 2 3 int str_len (char str[]) { 4 int i = 0; 5 while (str[i] != ' ') { 6 i++; 7 } 8 return i; 9 } 10 11 12 int main() { 13 char str[11] = "Hello world"; //C 语言允许字元阵列大小刚好只包含有文字内容的部分，但这样的字元阵列不能直接拿来给一般字串处理函式使用 14 printf("Length: %lu ", sizeof(str)); 15 printf("Length: %d ", str_len(str));// 字串长度 16 return 0; 17 } 18 19 Length: 11 20 Length: 12 21 22 Process returned 0 (0x0) execution time : 1.246 s 23 Press any key to continue.
1 #include <stdio.h> 2 3 int str_len (char str[]) { 4 int i = 0; 5 while (str[i] != ' ') { 6 i++; 7 } 8 return i; 9 } 10 11 12 int main() { 13 char str[12] = "Hello world"; 14 printf("Length: %lu ", sizeof(str)); 15 printf("Length: %d ", str_len(str));// 字串长度 16 return 0; 17 } 18 19 Length: 12 20 Length: 11 21 22 Process returned 0 (0x0) execution time : 1.217 s 23 Press any key to continue.
20.2 从键盘输入读入一行字的练习
1 #include <stdio.h> 2 void str_read(char[]); 3 4 int main() { 5 char str[15]; 6 str_read(str); 7 printf("%s ", str); 8 return 0; 9 } 10 11 12 void str_read(char str[]) { 13 int i = 0; 14 while (1) { 15 scanf("%c", &str[i]); 16 if (str[i] == ' ') 17 break; 18 i++; 19 } 20 str[i] = ' '; 21 } 22 23 24 panfangxu 25 panfangxu 26 27 Process returned 0 (0x0) execution time : 9.760 s 28 Press any key to continue.
22.3 关于读入字串的缓冲区溢位问题
1 #include <stdio.h> 2 3 void str_read(char[], int); 4 5 int main() { 6 char str[15]; 7 str_read(str, 7); 8 printf("%s ", str); 9 return 0; 10 } 11 12 void str_read(char str[], int n) { 13 int i; 14 for (i = 0; i < n; i++) { 15 scanf("%c", &str[i]); 16 if (str[i] == ' ') 17 break; 18 } 19 str[i] = ' '; 20 } 21 22 qwertyuiopasdfg 23 qwertyu 24 25 Process returned 0 (0x0) execution time : 7.086 s 26 Press any key to continue.
阵列大小在宣告定义后就不能改变
资源有限，不能改变大小就能解决问题
20.4使用scanf读入资料的问题
1 #include <stdio.h> 2 3 int main() { 4 int number; 5 if (scanf("%d", &number) == 1) { 6 printf("%d ", number); 7 8 }else { 9 printf("Error: Invalid input "); 10 11 } 12 return 0; 13 } 14 15 abc 16 Error: Invalid input 17 18 Process returned 0 (0x0) execution time : 2.767 s 19 Press any key to continue. 20 21 1 22 1 23 24 Process returned 0 (0x0) execution time : 3.133 s 25 Press any key to continue.
1 #include <stdio.h> 2 3 int main() { 4 int number; 5 while (scanf("%d", &number) != 1) { 6 printf("Error: Invalid input "); 7 8 } 9 printf("%d ", number); 10 return 0; 11 } 12 13 abc 14 Error: Invalid input 15 Error: Invalid input 16 ... 17 18 // scanf 函式读入资料失败的后遗症