9.1
1 #include <stdio.h> 2 #include <ctype.h> 3 #include <string.h> 4 5 #define N 100 6 7 int main (void) 8 { 9 int i = 0; 10 char strarray[N+1]; //= "Hello world! 3I'm here!"; 11 char *input = strarray; 12 char ch; 13 unsigned int cont = 0; 14 int ctr=0, spc=0, num=0, low=0, upp=0, puc=0, upr=0; 15 float ctrf=0, spcf=0, numf=0, lowf=0, uppf=0, pucf=0, uprf=0; 16 17 printf("Please enter a string: "); 18 19 while (( ch = getchar() ) != ' ') 20 { 21 *(input + i) = ch; 22 i++; 23 } 24 *(input + i) = ' '; 25 cont = strlen(input); 26 27 while (*input != ' ') 28 { 29 if (iscntrl(*input)) 30 ctr++; 31 if (isspace(*input)) 32 spc++; 33 if (isdigit(*input)) 34 num++; 35 if (islower(*input)) 36 low++; 37 if (isupper(*input)) 38 upp++; 39 if (ispunct(*input)) 40 puc++; 41 if (!(isprint(*input))) 42 upr++; 43 input++; 44 } 45 46 printf(" Totle char number is: Count = %d ", cont); 47 printf("cntrl = %d, space = %d, digit = %d ", ctr, spc, num); 48 printf("lower = %d, upper = %d, punct = %d ", low, upp, puc); 49 printf("uprint = %d ", upr); 50 51 ctrf = (float)ctr/(float)cont; 52 spcf = (float)spc/(float)cont; 53 numf = (float)num/(float)cont; 54 lowf = (float)low/(float)cont; 55 uppf = (float)upp/(float)cont; 56 pucf = (float)puc/(float)cont; 57 uprf = (float)upr/(float)cont; 58 59 printf(" Here is the percent of every count: "); 60 printf("cntrl = %.3f%% space = %.3f%% digit = %.3f%% ",ctrf*100 , spcf*100, numf*100); 61 printf("lower = %.3f%% upper = %.3f%% punct = %.3f%% ", lowf*100, uppf*100, pucf*100); 62 printf("uprnt = %.3f%% ", uprf*100); 63 64 getchar(); 65 return 0; 66 }
9.3
1 #include <stdio.h> 2 #include <string.h> 3 4 void my_strcpy(char *dst, char *src) 5 { 6 size_t len = 0, dstlen = 0, srclen = 0; 7 dstlen = strlen(dst); 8 srclen = strlen(src); 9 10 len = ( dstlen >= srclen ? srclen : dstlen ); 11 strncpy(dst, src, len); 12 } 13 14 void show_string(char *str) 15 { 16 while (*str != ' ') 17 printf("%c", *str++); 18 putchar(' '); 19 } 20 21 int main (void) 22 { 23 char dst[6] = "Hello"; 24 char src[10] = "I'm here!"; 25 char *dstp = dst; 26 char *srcp = src; 27 28 my_strcpy(dstp, srcp); 29 30 show_string(dstp); 31 show_string(srcp); 32 33 getchar(); 34 return 0; 35 }
9.4
1 #include <stdio.h> 2 #include <string.h> 3 4 #define M 12 5 #define N 16 6 7 void my_strcat(char *dst, char *src) 8 { 9 size_t len = 0, dstlen = 0, srclen = 0, restlen = 0; 10 dstlen = strlen(dst); 11 srclen = strlen(src); 12 13 len = ( (restlen = M - dstlen - 1) > srclen ? srclen : restlen ); 14 strncat(dst, src, len); 15 } 16 17 void show_string(char *str) 18 { 19 while (*str != ' ') 20 printf("%c", *str++); 21 putchar(' '); 22 } 23 24 int main (void) 25 { 26 char dst[M] = "Hello!"; 27 char src[N] = "I'm here!"; 28 char *dstp = dst; 29 char *srcp = src; 30 31 my_strcat(dst, src); 32 33 show_string(dstp); 34 show_string(srcp); 35 36 getchar(); 37 return 0; 38 }
9.5
1 #include <stdio.h> 2 #include <string.h> 3 4 #define M 12 5 #define N 16 6 7 void my_strncat(char *dest, char *src, int dest_len) 8 { 9 size_t len = 0, dstlen = 0, srclen = 0, restlen = 0; 10 dstlen = strlen(dest); 11 srclen = strlen(src); 12 13 len = ( (restlen = dest_len - dstlen - 1) > srclen ? srclen : restlen ); 14 strncat(dest, src, len); 15 } 16 17 void show_string(char *str) 18 { 19 while (*str != ' ') 20 printf("%c", *str++); 21 putchar(' '); 22 } 23 24 int main (void) 25 { 26 char dst[M] = "Hello!"; 27 char src[N] = "I'm here!"; 28 char *dstp = dst; 29 char *srcp = src; 30 31 my_strncat(dst, src, M); 32 33 show_string(dstp); 34 show_string(srcp); 35 36 getchar(); 37 return 0; 38 }
9.6
1 #include <stdio.h> 2 #include <string.h> 3 4 char *my_strcpy_end(char *dst, char *src) 5 { 6 int i, dstlen = 0, srclen = 0; 7 8 dstlen = strlen(dst); 9 srclen = strlen(src); 10 11 if ( dstlen >= srclen ) 12 strcpy(dst, src); 13 else 14 strncpy(dst, src, dstlen); 15 16 for ( i = 0; *(dst + i) != ' '; i++); 17 return dst + i; 18 } 19 20 int main (void) 21 { 22 char *p = NULL; 23 char dst[] = "Hello world"; 24 //char src[] = "123456789"; 25 char src[] = "123456789123456789"; 26 27 p = my_strcpy_end(dst, src); 28 29 printf("%c ", *(p - 1)); 30 31 getchar(); 32 return 0; 33 }
9.8
1 #include <stdio.h> 2 #include <string.h> 3 4 char *my_strnchr( char const *str, int ch, int which ) 5 { 6 int i; 7 char *p = NULL; 8 p = str; 9 10 for ( i = 0; i < which; i++) 11 { 12 if ( i != 0) 13 p++; 14 p = strchr(p, ch); 15 } 16 17 return p; 18 } 19 20 int main (void) 21 { 22 int i; 23 char str[] = "Hello world!"; 24 int chr = 'l'; 25 int which = 2; 26 27 char *find = my_strnchr(str, chr, which); 28 29 for (i = -1; i < 2; i++) 30 printf("%c ", *(find + i)); 31 putchar(' '); 32 33 getchar(); 34 return 0; 35 }
9.9
1 #include <stdio.h> 2 #include <string.h> 3 4 int count_chars(char const *str, char const *chars) 5 { 6 int count = 0, len = 0; 7 char *pos = NULL; 8 pos = str; 9 10 while (( pos = strpbrk(pos, chars) ) != NULL ) 11 { 12 count++; 13 pos++; 14 } 15 16 return count; 17 } 18 19 int main (void) 20 { 21 char str[] = "Hello world!"; 22 char chars[] = "ero"; 23 24 printf("%d ", count_chars(str, chars)); 25 26 getchar(); 27 return 0; 28 }
9.10
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <string.h> 4 #include <ctype.h> 5 6 int palindrome( char *string ) 7 { 8 int i, j = 0; 9 int len = strlen(string); 10 char *strcopy = NULL; 11 strcopy = malloc((len + 1)* sizeof(char)); 12 for (i = 0; i < len; i++) //将源字符串中的非字母字符去掉,并将剩下的字母转换为小写 13 { 14 if (isalpha(*(string + i))) 15 { 16 *(strcopy + j) = tolower( *(string + i) ); 17 j++; 18 } 19 } 20 *(strcopy + j) = ' '; 21 22 len = strlen(strcopy); 23 for (i = 0; i < (len / 2); i++) 24 { 25 if ( (*(strcopy + i)) != (*(strcopy + (len - i - 1) ) ) ) 26 return 0; 27 } 28 29 return 1; 30 } 31 32 int main (void) 33 { 34 char string[] = "Madam, I'm Adam!"; 35 int result = 0; 36 37 result = palindrome(string); 38 printf("%d ", result); 39 40 getchar(); 41 return 0; 42 }
9.11
1 #include <stdio.h> 2 #include <string.h> 3 4 int main (void) 5 { 6 char input[101]; 7 char chars[] = "the"; 8 int i = 0, count = 0; 9 char *pos = NULL; 10 11 printf("Please enter some words: "); 12 scanf("%s", input); 13 printf("%s ", input); 14 15 pos = input; 16 while ((pos = strstr(pos, chars)) != NULL) 17 { 18 pos++; 19 count++; 20 } 21 22 printf("There are %d "%s"!", count, chars); 23 24 getchar(); 25 getchar(); 26 return 0; 27 }
9.12 9.13 9.14
1 #include <stdio.h> 2 #include <string.h> 3 #include <ctype.h> 4 5 char *init_alp(char *temp) 6 { 7 int i; 8 char alp = 'A'; 9 10 for (i = 0; i < 26; i++) 11 { 12 13 *(temp + i) = alp; 14 alp++; 15 } 16 *(temp + i) = ' '; 17 18 return temp; 19 } 20 21 int prepare_key( char *key ) //生成key 22 { 23 int i = 0, j = 0, k = 0; 24 char alp[27]; 25 char *temp = alp; 26 27 char *p = NULL; 28 29 if (key == NULL) //key为空，退出 30 return 0; 31 32 for (i = 0; *(key + i) != ' '; i++) 33 if (!(isalpha(*(key + i)))) //key中含有非字母字符，退出） 34 return 0; 35 36 for (i = 0; *(key + i) != ' '; i++) 37 { 38 if (*(key + i) != ' ') //删除所有的空格 39 { 40 for (j = i + 1; *(key + j) != ' '; j++) //将重复的字母赋值为空格 41 { 42 if ( *(key + i) == *(key + j) ) 43 *(key + j) = ' '; 44 } 45 *(key + k) = toupper(*(key + i)); 46 k++; 47 } 48 } 49 *(key + k) = ' '; 50 51 temp = init_alp(temp); //初始化为大写字母表 52 p = temp; 53 while ((p = (strpbrk(p, key))) != NULL) //将字母表中含有key中的字母设置为空格 54 { 55 *p = ' '; 56 p++; 57 } 58 59 for (i = 0, k = 0; *(temp + i) != ' '; i++) //删除所有的空格 60 { 61 if (*(temp + i) != ' ') 62 { 63 *(temp + k) = *(temp + i); 64 k++; 65 } 66 } 67 *(temp + k) = ' '; 68 69 key = strcat(key, temp); 70 71 return 1; 72 } 73 74 void encrypt( char *data, char const *key ) //给数据加密 75 { 76 int i, state; 77 char temp[27]; 78 char *init = NULL; 79 char *p = NULL; 80 char chg; 81 82 init = init_alp(temp); 83 84 for (i = 0; *(data + i) != ' '; i++) 85 { 86 if (isalpha(*(data + i))) 87 { 88 if (isupper(*(data + i))) 89 state = 1; 90 else 91 { 92 *(data + i) = toupper(*(data + i)); 93 state = 0; 94 } 95 p = strchr(init, *(data + i)); 96 chg = *(key + (p - init)); 97 *(data + i) = state ? chg : tolower(chg); 98 } 99 } 100 } 101 102 void decrypt( char *data, char const *key ) //给数据解密 103 { 104 int i, state; 105 char temp[27]; 106 char *init = NULL; 107 char *p = NULL; 108 char chg; 109 110 init = init_alp(temp); 111 112 for (i = 0; *(data + i) != ' '; i++) 113 { 114 if (isalpha(*(data + i))) 115 { 116 if (isupper(*(data + i))) 117 state = 1; 118 else 119 { 120 *(data + i) = toupper(*(data + i)); 121 state = 0; 122 } 123 p = strchr(key, *(data + i)); 124 chg = *(init + (p - key)); 125 *(data + i) = state ? chg : tolower(chg); 126 } 127 } 128 } 129 130 int main (void) 131 { 132 char key[28] = "Hellomnnnnab"; 133 char temp[28]; 134 char *key_m = temp; 135 char data[] = "Hello world!"; 136 137 key_m = init_alp(key_m); 138 printf("%s ", key); //显示输入的key 139 140 if (prepare_key(key)) 141 { 142 printf(" Alpha: "); //显示大写字母表 143 printf("%s ", key_m); 144 printf(" Key: "); //显示生成的key秘钥 145 printf("%s ", key); 146 147 printf(" Encode: "); 148 printf("%s ", data); 149 encrypt(data, key); //加密 150 printf("%s ", data); 151 152 printf(" Decode: "); 153 printf("%s ", data); 154 decrypt(data, key); //解密 155 printf("%s ", data); 156 } 157 else 158 printf("Key error! "); 159 160 161 getchar(); 162 return 0; 163 }
9.15
1 #include <stdio.h> 2 #include <string.h> 3 #include <ctype.h> 4 5 void dollars(char *dest, char const *src) 6 { 7 int i, j, srclen = 0, offset = 0, state = 0; 8 int a = 0, b = 0; 9 char *destbak = NULL; 10 destbak = dest; 11 12 srclen = strlen(src); 13 *dest++ = '$'; 14 15 if (srclen >= 3) 16 { 17 a = (srclen - 2) / 3; 18 b = (srclen - 2) % 3; 19 20 for (i = 0; (i < a); i++) 21 { 22 if ( i == 0 ) 23 { 24 for (j = 0; j < b; j++) 25 { 26 *(dest++) = *(src++); 27 } 28 } 29 30 if (b != 0) 31 *(dest++) = ','; 32 33 for (j = 0; j < 3; j++) 34 *(dest++) = *(src++); 35 } 36 37 if ((a == 0) && (b != 0)) 38 { 39 for (j = 0; j < b; j++) 40 { 41 *(dest++) = *(src++); 42 } 43 } 44 *((dest++)) = '.'; 45 46 for ( ; *(src) != ' ';dest++, src++) 47 *(dest) = *(src); 48 *(dest) = ' '; 49 } 50 else 51 { 52 memset(dest, '0', 4); 53 *(++dest) = '.'; 54 dest++; 55 for (i = 0; i < 2 - srclen; i++) 56 *(dest++) = '0'; 57 58 for (i = 0; i < srclen; i++) 59 *(dest + i) = *(src + i); 60 } 61 } 62 63 int dollchk(char *src) //检查要处理的数据中是否有非数字字符 64 { 65 int i; 66 for (i = 0; *(src + i) != ' '; i++) 67 { 68 if (!isdigit(*(src + i))) 69 { 70 return 0; 71 } 72 } 73 return 1; 74 } 75 76 int main (void) 77 { 78 char temp[20] = { 0 }; //目标缓存 79 char dollar[20]; 80 char *dest = temp; 81 int state = 0; 82 83 printf("Please enter some numbers: "); 84 scanf("%s", dollar); 85 86 state = dollchk(dollar); 87 if (!state) //检查要处理的数据中含有非数字字符，报错，退出 88 { 89 printf("Data error! "); 90 getchar(); 91 getchar(); 92 return 0; 93 } 94 95 printf("%s ", dest); 96 printf("%s ", dollar); 97 98 dollars(dest, dollar); 99 if (*dest != ' ') 100 printf("%s ", dest); 101 102 getchar(); 103 getchar(); 104 return 0; 105 }
9.16
1 #include <stdio.h> 2 #include <string.h> 3 4 int format( char *format_string, char const *digit_string ) 5 { 6 int formatlen = strlen(format_string); 7 int digitlen = strlen(digit_string); 8 int i, j, k; 9 char *p = NULL; 10 11 if (formatlen < digitlen) 12 return 0; 13 if ((*digit_string) == ' ') 14 return 0; 15 16 if ((p = strchr(format_string, '.')) != NULL) 17 { 18 if ((k = formatlen - (p - format_string)) > digitlen) 19 { 20 for (i = formatlen, j = digitlen; j >= 0; i--, j--, k--) 21 { 22 *(format_string + i) = *(digit_string + j); 23 } 24 25 for (; k > 0; i--, k--) 26 { 27 *(format_string + i) = '0'; 28 } 29 30 if ( (*(format_string + i) == '.') ) 31 { 32 i--; 33 *(format_string + i) = '0'; 34 } 35 36 for (i--; i >= 0; i--) 37 { 38 *(format_string + i) = ' '; 39 } 40 } 41 else 42 { 43 for (i = formatlen, j = digitlen; j >= 0; i--, j--) 44 { 45 if ( (*(format_string + i) == ',') 46 || (*(format_string + i) == '.') ) 47 i--; 48 *(format_string + i) = *(digit_string + j); 49 } 50 for (; i >= 0; i--) 51 *(format_string + i) = ' '; 52 } 53 } 54 55 return 1; 56 } 57 58 int main (void) 59 { 60 char formats[] = "###,###.#####"; 61 char const digits[] = "123"; 62 63 printf("%s ", formats); 64 printf("%s ", digits); 65 if (format(formats, digits)) 66 printf("%s ", formats); 67 else 68 printf("Data error! "); 69 70 getchar(); 71 return 0; 72 }
9.17