perl中sprintf函数的使用方法。

对于某些字符串，需要输入为特定的格式，通过sprintf可以很方便的完成，不需要专门进行其他处理。

perl中的sprintf的用法如下：

sprintf FORMAT, LIST

比如：

$result = sprintf("%08d",$number);让$number有8个前导零。

$rounded = sprintf("%.3f",$number);

让小数点后有3位数字。

sprintf允许的如下常用的转换：

%% 百分号

%c 把给定的数字转化为字符

%s 字符串

%d
带符号整数，十进制

%u 无符号整数，十进制

%o 无符号整数，八进制

%x 无符号整数，十六进制

%e 浮点数，科学计算法

%f 浮点数，用于固定十进制计数

%g 浮点数，包括%e和%f

%X like %x, but using upper-case letters

%E like %e, but using an upper-case "E"

%G like %g, but with an upper-case "E" (if applicable)

%b an unsigned integer, in binary

%B like %b, but using an upper-case "B" with the # flag

%p a pointer (outputs the Perl value's address in hexadecimal)

%n special: *stores* the number of characters output so far

into the next variable in the parameter list

通过$1,$2等可以改变顺序：

printf '%2$d %1$d', 12, 34; # prints "34 12"

printf '%3$d %d %1$d', 1, 2, 3; # prints "3 1 1"

printf '<% d>', 12; # prints "< 12>"

printf '<%+d>', 12; # prints "<+12>"

printf '<%6s>', 12; # prints "< 12>"

printf '<%-6s>', 12; # prints "<12 >"

printf '<%06s>', 12; # prints "<000012>"

printf '<%#o>', 12; # prints "<014>"

printf '<%#x>', 12; # prints "<0xc>"

printf '<%#X>', 12; # prints "<0XC>"

printf '<%#b>', 12; # prints "<0b1100>"

printf '<%#B>', 12; # prints "<0B1100>"

printf '<%f>', 1; # prints "<1.000000>"

printf '<%.1f>', 1; # prints "<1.0>"

printf '<%.0f>', 1; # prints "<1>"

printf '<%e>', 10; # prints "<1.000000e+01>"

printf '<%.1e>', 10; # prints "<1.0e+01>"

printf '<%.6d>', 1; # prints "<000001>"

printf '<%+.6d>', 1; # prints "<+000001>"

printf '<%-10.6d>', 1; # prints "<000001 >"

printf '<%10.6d>', 1; # prints "< 000001>"

printf '<%010.6d>', 1; # prints "< 000001>"

printf '<%+10.6d>', 1; # prints "< +000001>"

printf '<%.6x>', 1; # prints "<000001>"

printf '<%#.6x>', 1; # prints "<0x000001>"

printf '<%-10.6x>', 1; # prints "<000001 >"

printf '<%10.6x>', 1; # prints "< 000001>"

printf '<%010.6x>', 1; # prints "< 000001>"

printf '<%#10.6x>', 1; # prints "< 0x000001>"

printf '<%.5s>', "truncated"; # prints "<trunc>"

printf '<%10.5s>', "truncated"; # prints "< trunc>"

printf "%2/$d %d/n", 12, 34; # will print "34

"

printf "%2/$d %d %d/n", 12, 34; # will print "34

4/n"

printf "%3/$d %d %d/n", 12, 34, 56; # will print "56

4/n"

printf "%2/$*3/$d %d/n", 12, 34, 3; # will print " 3

n"