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ctype.h里的函數(shù) 1 字符測(cè)試函數(shù) 1> 函數(shù)原型均為int isxxxx(int) 2> 參數(shù)為int, 任何實(shí)參均被提升成整型 3> 只能正確處理處于[0, 127]之間的值 2 字符映射函數(shù) 1> 函數(shù)原型為int toxxxx(int) 2> 對(duì)參數(shù)進(jìn)行檢測(cè), 若符合范圍則轉(zhuǎn)換, 否則不變 int tolower(int); 'A'~'Z' ==> 'a'~'z' int toupper(int); 'a'~'z' ==> 'A'~'Z' @函數(shù)名稱: isalpha 函數(shù)原型: int isalpha(int ch); 函數(shù)功能: 檢查ch是否是字母. 函數(shù)返回: 是字母返回1 ,否則返回 0. 參數(shù)說(shuō)明: 所屬文件 <ctype.h> #include <stdio.h> #include <ctype.h> int main() { char ch1='*'; char ch2='a'; if(isalnum(ch1)!=0) printf("%c is the ASCII number or alphebet\n",ch1); else printf("%c is not the ASCII number nor alphebet\n",ch1); if(isalnum(ch2)!=0) printf("%c is the ASCII number or alphebet\n",ch2); else printf("%c is not the ASCII number nor alphebet\n",ch2); return 0; } @函數(shù)名稱: iscntrl 函數(shù)原型: int iscntrl(int ch); 函數(shù)功能: 檢查ch是否控制字符(其ASCII碼在0和0x1F之間,數(shù)值為 0-31). 函數(shù)返回: 是返回 1,否則返回 0. 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> char chars[]={'A',0x09,'Z'}; #define SIZE sizeof(chars)/sizeof(char) int main() { int i; for(i=0;i<SIZE;i++){ printf("Char %c is %sa Control character\n", chars,(iscntrl(chars))?"":"not"); } return 0; } @函數(shù)名稱: isdigit 函數(shù)原型: int isdigit(int ch); 函數(shù)功能: 檢查ch是否是數(shù)字(0-9) 函數(shù)返回: 是返回1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> int main() { char ch1='1'; char ch2='a'; if(isdigit(ch1)!=0) printf("%c is the ASCII number\n",ch1); else printf("%c is not the ASCII number\n",ch1); if(isdigit(ch2)!=0) printf("%c is the ASCII number\n",ch2); else printf("%c is not the ASCII number\n",ch2); return 0; } @函數(shù)名稱: isgraph 函數(shù)原型: int isgraph(int ch); 函數(shù)功能: 檢查ch是否可顯示字符(其ASCII碼在ox21到ox7E之間),不包括空格 函數(shù)返回: 是返回1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> int main() { char ch1=' '; char ch2='a'; if(isgraph(ch1)!=0) printf("%c is the ASCII printable character\n",ch1); else printf("%c is not the ASCII printable character\n",ch1); if(isgraph(ch2)!=0) printf("%c is the ASCII printable character\n",ch2); else printf("%c is not the ASCII printable character\n",ch2); return 0; } @函數(shù)名稱: islower 函數(shù)原型: int islower(int ch); 函數(shù)功能: 檢查ch是否小寫(xiě)字母(a-z) 函數(shù)返回: 是返回1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> char chars[]={'A','a','z','Z'}; #define SIZE sizeof(chars)/sizeof(char) int main() { int i; for(i=0;i<SIZE;i++){ printf("Char %c is %sa lowercase character\n",chars,(islower(chars))?"":"not"); } return 0; } @函數(shù)名稱: tolower 函數(shù)原型: int tolower(int ch); 函數(shù)功能: 將ch字符轉(zhuǎn)換為小寫(xiě)字母 函數(shù)返回: 返回ch所代表的字符的小寫(xiě)字母 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <stdlib.h> #include <ctype.h> int main() { char x='a', y='b',z='A',w='*'; printf("Character %c to lower is %c\n",x,tolower(x)); printf("Character %c to lower is %c\n",y,tolower(y)); printf("Character %c to lower is %c\n",z,tolower(z)); printf("Character %c to lower is %c\n",w,tolower(w)); return 0; } @函數(shù)名稱: toupper 函數(shù)原型: int toupper(int ch); 函數(shù)功能: 將ch字符轉(zhuǎn)換成大寫(xiě)字母 函數(shù)返回: 與ch相應(yīng)的大寫(xiě)字母 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <stdlib.h> #include <ctype.h> int main() { char x='a', y='b',z='A',w='*'; printf("Character %c to upper is %c\n",x,toupper(x)); printf("Character %c to upper is %c\n",y,toupper(y)); printf("Character %c to upper is %c\n",z,toupper(z)); printf("Character %c to upper is %c\n",w,toupper(w)); return 0; } @函數(shù)名稱: isalnum 函數(shù)原型: int isalnum(int ch); 函數(shù)功能: 檢查ch是否是字母或數(shù)字 函數(shù)返回: 是字母或數(shù)字返回1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> int main() { char ch1 ='*'; char ch2 ='a'; if(isalnum(ch1)!=0) printf("%c is the ASCII number or alphebet\n",ch1); else printf("%c is not the ASCII number nor alphebet\n",ch1); if(isalnum(ch2)!=0) printf("%c is the ASCII number or alphebet\n",ch2); else printf("%c is not the ASCII number nor alphebet\n",ch2); return 0; } @函數(shù)名稱: isprint 函數(shù)原型: int isprint(int ch); 函數(shù)功能: 檢查ch是否是可打印字符(包括空格),其ASCII碼在ox20到ox7E之間 函數(shù)返回: 是返回1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> int main() { char ch1='\n'; char ch2='a'; if(isprint(ch1)!=0) printf("%c is the ASCII printable charcater\n",ch1); else printf("%c is not the ASCII printable charcater\n",ch1); if(isprint(ch2)!=0) printf("%c is the ASCII printable charcater\n",ch2); else printf("%c is not the ASCII printable charcater\n",ch2); return 0; } @函數(shù)名稱: ispunct 函數(shù)原型: int ispunct(int ch); 函數(shù)功能: 檢查ch是否是標(biāo)點(diǎn)字符(不包括空格),即除字母,數(shù)字和空格以外的所有可打印字符 函數(shù)返回: 是返回1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include<ctype.h> int main() { char ch1=','; char ch2='a'; if(ispunct(ch1)!=0) printf("%c is the ASCII punct\n",ch1); else printf("%c is not the ASCII punct\n",ch1); if(ispunct(ch2)!=0) printf("%c is the ASCII punct\n",ch2); else printf("%c is not the ASCII punct\n",ch2); return 0; } @函數(shù)名稱: isspace 函數(shù)原型: int isspace(int ch); 函數(shù)功能: 檢查ch是否是空格符和跳格符(控制字符)或換行符 函數(shù)返回: 是返回1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> int main() { char ch1=' '; char ch2='a'; if(isspace(ch1)!=0) printf("%c is the space charcater\n",ch1); else printf("%c is not the space charcater\n",ch1); if(isspace(ch2)!=0) printf("%c is the space charcater\n",ch2); else printf("%c is not the space charcater\n",ch2); return 0; } @函數(shù)名稱: isupper 函數(shù)原型: int isupper(int ch); 函數(shù)功能: 檢查ch是否是大寫(xiě)字母(A-Z) 函數(shù)返回: 是返回1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> char chars[]={'A','a','z','Z'}; #define SIZE sizeof(chars)/sizeof(char) int main() { int i; for(i=0;i<SIZE;i++){ printf("Char %c is %san uppercase character\n", chars,(isupper(chars))?"":"not"); } return 0; } @函數(shù)名稱: isxdigit 函數(shù)原型: int isxdigit(int ch); 函數(shù)功能: 檢查ch是否是一個(gè)16進(jìn)制數(shù)學(xué)字符(即0-9,或A-F,或a-f) 函數(shù)返回: 是返回 1,否則返回0 參數(shù)說(shuō)明: 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> int main() { char ch1='1'; char ch2='a'; if(isxdigit(ch1)!=0) printf("%c is the ASCII hexadecimal number\n",ch1); else printf("%c is not the ASCII hexadecimal number\n",ch1); if(isxdigit(ch2)!=0) printf("%c is the ASCII hexadecimal number\n",ch2); else printf("%c is not the ASCII hexadecimal number\n",ch2); return 0; } @函數(shù)名稱: isascii 函數(shù)原型: int isascii(int ch) 函數(shù)功能: 測(cè)試參數(shù)是否是ASCII碼0-127 函數(shù)返回: 非零-是，0-不是 參數(shù)說(shuō)明: ch-被測(cè)參數(shù) 所屬文件: <ctype.h> #include <stdio.h> #include <ctype.h> char chars[]={'A',0x80,'Z'}; #define SIZE sizeof(chars)/sizeof(char) int main() { int i; for(i=0;i<SIZE;i++) { printf("Char %c is %san ASCII character\n", chars,(isascii(chars))?"":"not"); } return 0; }
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