求用c语言求出一段字符序列中有多少个字母？多少个数字？ 多少个空格？多少个其他字符？

#include <stdio.h>

int main()
{
int nNum[4] = {0};

char str[100];
gets( str );

for( int i = 0; str[i] ; i ++)
{
if( str[i] == ' ' )
{
nNum[0] ++;
}
else if( str[i] >= '0' && str[i] <= '9' )
{
nNum[1] ++;
}
else if ( (str[i] >= 'a' && str[i] <= 'z' )|| (str[i] >= 'A' && str[i] <= 'Z' ))
{
nNum[2] ++;
}
else
{
nNum[3] ++;
}
}

printf( "空格数:%d\n" , nNum[0] );
printf( "数字数:%d\n" , nNum[1] );
printf( "字母数:%d\n" , nNum[2] );
printf( "其他数:%d\n" , nNum[3] );

return 0;
}