------- iOS培训、android培训、java培训、期待与您交流! ---------- #import <Foundation/Foundation.h> int main(int argc, const char * argv[]) { @autoreleasepool { //NSString空间和内容都不可变 NSString *s1 = @"Jack";//常量区 NSLog(@"s1 addr = %p",s1); s1 = @"Rose"; NSLog(@"s1 addr = %p",s1); //NSMutableString空间和内容都可变 NSMutableString *s2 = [NSMutableString stringWithFormat:@"Jack"];//堆区 NSLog(@"s2 = %@",s2); NSLog(@"s2 addr = %p",s2); [s2 appendString:@"&Rose"]; NSLog(@"s2 = %@",s2); NSLog(@"s2 addr = %p",s2); NSMutableString *s3 = [NSMutableString string]; NSLog(@"s3 = %@",s3); for (int i = 0; i < 10; i++) { [s3 appendString:@"itcast"]; } NSLog(@"s3 = %@",s3); } return 0; } |