Format specifiers are used together with theprintf()function to tell the compiler what type of data the variable is storing. It is basically aplaceholderfor the variable value. A format specifier starts with a percentage sign%, followed by a character. ...
然而即使使用snprintf()替换sprintf()也无法完全保护程序不受格式化字符串的攻击。这些攻击通过直接将格式说明符(formatspecifiers)(%d,%s,%n等)传递到输出函数接收缓冲区来进行。 例如,以下的代码就是不安全的snprintf(buffer,sizeof(buffer),string)这种情况下,可以在字符串中插入格式说明符来操纵内存的栈,来写入攻击...
NSString *magicString = [NSString stringWithFormat:@"The magic number is %i", magicNumber]; 有效的格式化说明符被“String Format Specifiers”描述,更多一般的信息关于字符串的看String Programming Guide.文档 NSNumber类的实例表示数值: 这个NSNumber类是用来表示任何基本的C数据类型:包括char double float int...
Format Specifiers in the printf() Function in C The syntax of printf() function is: int printf(const char* format, ...); This function writes the string stored in the format variable on the standard output console. If this string includes format specifiers,i.e., some sub-strings starti...
对于NSString类来说,description方法将返回其代表的字符串数据。若需要了解 更多关于NSLog()函数和NSString的格式化说明符的内容,请参见String Format Specifiers。 方法可以返回一个值 既然可以向方法的形参传入数值,那么方法也可以返回数值。目前为止本章节的所有方法的返回值都是void。C语言void关键字意味着方法不会...
在使用诸如NSLog, [NSString stringWithFormat:]之类的函数时,都是基于c/c++风格的字符串格式化工作的. Table 1 Format specifiers supported by the NSString formatting methods and CFString formatting functions 平台依赖 Mac OS X uses several data types—NSInteger, NSUInteger,CGFloat, and CFIndex—to provide...
int printf(format_string, expr1, expr2, . . ); The first argument of this function is a string that is interspersed with one or more format specifiers. There may be one or more expressions as argument after the first. The compiler substitutes each format specifier with the value of its ...
int printf(format_string, expr1, expr2, . . ); The first argument of this function is a string that is interspersed with one or more format specifiers. There may be one or more expressions as argument after the first. The compiler substitutes each format specifier with the value of its ...
uint64的格式化请用%llu , int64的格式化请用%lld 格式定义 The format specifiers supported by the NSString...
The number of these parameters should, at least, be equal to the number of values indicated in the format specifiers. The function ignores any additional arguments. Return value: This function returns an int value specifying the number of characters written in the resultant string. This number of...