如何判断一个字符串是数值还是字符串？

[xiaofengpangpang]

一个字符串数组，比如str[1]="123"
str[2]="23"
str[3]="汉字汉字汉字"

如何判断字符串str里是数值还是汉字字符？

[shadowWind]

读ascii码

[zhangshengyu]

也可以用atoi 如果字符串全是0或其他字符就返回0，其他返回数字

[allenq]

BOOL CheckNumber( char* your_str )
{
int nLen = str(your_str);
for( int i=0; i<nLen; i++)
{
if( your_str[i] > '0' || your_str[i] <'1' )//判断其中字符是否为数字
{
return FALSE;
}
}
return TRUE;
}

如果有汉字等字符, 还应该判断是否是双字节字符IsDBCSLeadByte(*ptr)

[aspnetwuxueyou]

isalnum
Alphanumeric (A – Z, a – z, or 0 – 9).
isalpha
Alphabetic (A – Z or a – z).
__isascii
ASCII character (0x00 – 0x7F).
iscntrl
Control character (0x00 – 0x1F or 0x7F).
__iscsym
Letter, underscore, or digit.
__iscsymf
Letter or underscore.
isdigit
Decimal digit (0 – 9).
isgraph
Printable character except space ( ).
islower
Lowercase letter (a – z).
isprint
Printable character including space (0x20 – 0x7E).
ispunct
Punctuation character.
isspace
White-space character (0x09 – 0x0D or 0x20).
isupper
Uppercase letter (A – Z).
isxdigit
Hexadecimal digit (A – F, a – f, or 0 – 9).
For the isw routines, the result of the test for the specified condition is independent of locale. The test conditions for the isw functions are as follows:

iswalnum
iswalpha or iswdigit.
iswalpha
Any wide character that is one of an implementation-defined set for which none of iswcntrl, iswdigit, iswpunct, or iswspace is nonzero. iswalpha returns nonzero only for wide characters for which iswupper or iswlower is nonzero.
iswascii
Wide-character representation of ASCII character (0x0000 – 0x007F).
iswcntrl
Control wide character.
iswctype
Character has property specified by the desc argument. For each valid value of the desc argument of iswctype, there is an equivalent wide-character classification routine, as shown in the following table:

[yuantao]

用atoi把,最方便不过了
#include <stdlib.h>
#include <stdio.h>

void main( void )
{
char *s; double x; int i; long l;

s = " -2309.12E-15"; /* Test of atof */
x = atof( s );
printf( "atof test: ASCII string: %s\tfloat: %e\n", s, x );

s = "7.8912654773d210"; /* Test of atof */
x = atof( s );
printf( "atof test: ASCII string: %s\tfloat: %e\n", s, x );

s = " -9885 pigs"; /* Test of atoi */
i = atoi( s );
printf( "atoi test: ASCII string: %s\t\tinteger: %d\n", s, i );

s = "98854 dollars"; /* Test of atol */
l = atol( s );
printf( "atol test: ASCII string: %s\t\tlong: %ld\n", s, l );
}


Output

atof test: ASCII string: -2309.12E-15 float: -2.309120e-012
atof test: ASCII string: 7.8912654773d210 float: 7.891265e+210
atoi test: ASCII string: -9885 pigs integer: -9885
atol test: ASCII string: 98854 dollars long: 98854