如何从字符串中删除空格和特殊字符？
我在谷歌上搜索时没有找到一个可行的答案，大多数与其他语言有关，但并不是C语言。其中大部分提到了使用正则表达式，但这并非C标准。
删除简单的空格很容易：
char str[50] = "Remove The Spaces!!";
接下来是一个带有if语句的简单循环：
if (str[i] != ' ');
RemoveTheSpaces!!
我应该在if语句中添加什么内容，以便它能够识别特殊字符并将其删除？
我的特殊字符定义:
Characters not included in this list:
A-Z a-z 0-9
这可能不是最高效的方法，但它可以相对快速地完成工作。
注意：此代码需要包含<string.h>和<ctype.h>
char str[50] = "Remove The Spaces!!";
char strStripped[50];
int i = 0, c = 0; /*I'm assuming you're not using C99+*/
for(; i < strlen(str); i++)
{
if (isalnum(str[i]))
{
strStripped[c] = str[i];
c++;
}
}
strStripped[c] = '\0';
strStripped[c]='\0';。 - Heath Hunnicutt// 风格的注释也不被支持。 - user405725strlen() 会导致糟糕的（二次）性能，而不是线性性能。请使用 int len = strlen(str);，然后在循环条件中测试 len。 - Jonathan Leffler使用if语句：
if (str[i] != ' ');
通过一些逻辑（字符必须在a-z或A-Z或0-9范围内）：
If ( !('a' <= str[i] && 'z' >= str[i]) &&
!('A' <= str[i] && 'Z' >= str[i]) &&
!('0' <= str[i] && '9' >= str[i])) then ignore character.
这只是一个愚蠢的建议。
char ordinary[CHAR_MAX] = {
['A']=1,['B']=1,['C']=1,['D']=1,['E']=1,['F']=1,['G']=1,['H']=1,['I']=1,
['J']=1,['K']=1,['L']=1,['M']=1,['N']=1,['O']=1,['P']=1,['Q']=1,['R']=1,
['S']=1,['T']=1,['U']=1,['V']=1,['W']=1,['X']=1,['Y']=1,['Z']=1,
['a']=1,['b']=1,['c']=1,['d']=1,['e']=1,['f']=1,['g']=1,['h']=1,['i']=1,
['j']=1,['k']=1,['l']=1,['m']=1,['n']=1,['o']=1,['p']=1,['q']=1,['r']=1,
['s']=1,['t']=1,['u']=1,['v']=1,['w']=1,['x']=1,['y']=1,['z']=1,
['0']=1,['1']=1,['2']=1,['3']=1,['4']=1,['5']=1,['6']=1,['7']=1,['8']=1,
['9']=1,
};
int is_special (int c) {
if (c < 0) return 1;
if (c >= CHAR_MAX) return 1;
return !ordinary[c];
}
void remove_spaces_and_specials_in_place (char *str) {
if (str) {
char *p = str;
for (; *str; ++str) {
if (!is_special(*str)) *p++ = *str;
}
*p = '\0';
}
}
有数百万种不同的方法可以完成这个任务。这里只是一个示例，它不使用任何额外的存储，并且“原地”执行了不需要的字符删除：
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
static void my_strip(char *data)
{
unsigned long i = 0; /* Scanning index */
unsigned long x = 0; /* Write back index */
char c;
/*
* Store every next character in `c` and make sure it is not '\0'
* because '\0' indicates the end of string, and we don't want
* to read past the end not to trigger undefined behavior.
* Then increment "scanning" index so that next time we read the
* next character.
*/
while ((c = data[i++]) != '\0') {
/* Check if character is either alphabetic or numeric. */
if (isalnum(c)) {
/*
* OK, this is what we need. Write it back.
* Note that `x` will always be either the same as `i`
* or less. After writing, increment `x` so that next
* time we do not overwrite the previous result.
*/
data[x++] = c;
}
/* else — this is something we don't need — so we don't increment the
`x` while `i` is incremented. */
}
/* After all is done, ensure we terminate the string with '\0'. */
data[x] = '\0';
}
int main()
{
/* This is array we will be operating on. */
char data[512];
/* Ask your customer for a string. */
printf("Please enter a string: ");
if (fgets(data, sizeof(data), stdin) == NULL) {
/* Something unexpected happened. */
return EXIT_FAILURE;
}
/* Show the customer what we read (just in case :-)) */
printf("You have entered: %s", data);
/*
* Call the magic function that removes everything and leaves
* only alphabetic and numberic characters.
*/
my_strip(data);
/*
* Print the end result. Note that newline (\n) is there
* when we read the string
*/
printf("Stripped string: %s\n", data);
/* Our job is done! */
return EXIT_SUCCESS;
}
我在代码中添加了许多注释，希望它们足够清晰，不需要解释。希望能对你有所帮助。祝好运！
#include <stdio.h>
#include <string.h>
main()
{
int i=0, j=0;
char c;
char buff[255] = "Remove The Spaces!!";
for(; c=buff[i]=buff[j]; j++){
if(c>='A' && c<='Z' || c>='a' && c<='z' || c>='0' && c<='9'){
i++;
}
}
printf("char buff[255] = \"%s\"\n", buff);
}
include < stdio.h >
int main()
{
char a[100];
int i;
printf("Enter the character : ");
gets(a);
for (i = 0; a[i] != '\0'; i++) {
if ((a[i] >= 'a' && a[i] <= 'z') || (a[i] >= 'A' && a[i] <= 'Z')
|| (a[i] - 48 >= 0 && a[i] - 48 <= 9)) {
printf("%c", a[i]);
} else {
continue;
}
}
return 0;
}
这是ASCII码范围
字符: 十进制
0:48, 9:57
A:65, Z:90
a:97, z:122
试试这个：
char str[50] = "Remove The Spaces!!";
int i =0;
for(; i<strlen(str); i++)
{
if(str[i]>=48 && str[i]<=57 || str[i]>=65 && str[i]<=90 || str[i]>=97 && str[i]<=122)
//This is equivalent to
//if(str[i]>='0' && str[i]<='9' || str[i]>='A' && str[i]<='Z' || str[i]>='a' && str[i]<='z')
printf("alphaNumeric:%c\n", str[i]);
else
{
printf("special:%c\n", str[i]);
//remove that
}
}
char数组。您可以用b替换a，但没有简单的方法从数组中删除字符索引，因此仍然会留下空洞。虽然，如果只是为了打印，您可以遍历数组，如果它不在ascii值范围内的a-zA-Z0-9，则跳过执行任何操作并转到下一个字符。在我看来，这通常是可能时最容易做的事情。否则，您需要复制到新缓冲区。 - Jite