sscanf

sscanf 是C函数库 <stdio.h> 中的一个函数, 主要用来从字符串读取格式化输入, 参考: https://www.runoob.com/cprogramming/c-function-sscanf.html

int sscanf(const char *str, const char *format, ...)

把 str 通过 format 格式化给后面的参数

#include <stdio.h>

int main(int argc, const char * argv[]) {
    char *str = "0xf";
    int value = 0;
    // 把字符串str, 格式化赋值给 vaue, 格式化规则是: %X (%X是十六进制格式符, 0xf是16进制的f,对应十字制对应15)
    sscanf(str, "%X", &value);
    printf("%d\n", value); //15
    return 0;
}

image.png

实际项目中的一个示例, RGB颜色转换:

#import <Foundation/Foundation.h>

NSUInteger hexStrToInt(NSString *str) {
    uint32_t result = 0;
    sscanf([str UTF8String], "%X", &result);
    return result;
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // NSString *rgb = @"FF0012";
        NSLog(@"%lu", hexStrToInt(@"FF")); // 255
        NSLog(@"%lu", hexStrToInt(@"00")); // 0
        NSLog(@"%lu", hexStrToInt(@"12")); // 18
    }
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
   int day, year;
   char weekday[20], month[20], dtm[100];

   strcpy( dtm, "Saturday March 25 1989" );
   sscanf( dtm, "%s %s %d  %d", weekday, month, &day, &year );

   printf("%s %d, %d = %s\n", month, day, year, weekday ); // March 25, 1989 = Saturday
    
   return(0);
}