是否有一种干净的、最好是标准的方法从 C 中的字符串中修剪前导和尾随空格?我会自己动手,但我认为这是一个同样常见的解决方案的常见问题。
如果可以修改字符串:
// Note: This function returns a pointer to a substring of the original string. // If the given string was allocated dynamically, the caller must not overwrite // that pointer with the returned value, since the original pointer must be // deallocated using the same allocator with which it was allocated. The return // value must NOT be deallocated using free() etc. char *trimwhitespace(char *str) { char *end; // Trim leading space while(isspace((unsigned char)*str)) str++; if(*str == 0) // All spaces? return str; // Trim trailing space end = str + strlen(str) - 1; while(end > str && isspace((unsigned char)*end)) end--; // Write new null terminator character end[1] = '\0'; return str; }
如果你不能修改字符串,那么你可以使用基本相同的方法:
// Stores the trimmed input string into the given output buffer, which must be // large enough to store the result. If it is too small, the output is // truncated. size_t trimwhitespace(char *out, size_t len, const char *str) { if(len == 0) return 0; const char *end; size_t out_size; // Trim leading space while(isspace((unsigned char)*str)) str++; if(*str == 0) // All spaces? { *out = 0; return 1; } // Trim trailing space end = str + strlen(str) - 1; while(end > str && isspace((unsigned char)*end)) end--; end++; // Set output size to minimum of trimmed string length and buffer size minus 1 out_size = (end - str) < len-1 ? (end - str) : len-1; // Copy trimmed string and add null terminator memcpy(out, str, out_size); out[out_size] = 0; return out_size; }