awk における算術演算

四則演算

scpt6_1.awk

#!/usr/local/bin/gawk -f
# scpt6_1.awk

BEGIN{
    print 7 + 2
    print 7 - 2
    print 7 * 2
    print 7 / 2
}

scpt6_1.awk の実行結果は:

[cactus:~/code_awk/tuts]% ./scpt6_1.awk
9
5
14
3.5

独特の省略法 ++ –

scpt6_2.awk

#!/usr/local/bin/gawk -f
# scpt6_2.awk

BEGIN{
    x = 5
    x += 3 # x = x + 3 と同じ
    print x

    y = 5
    y -= 3 # y = y - 3 と同じ
    print y

    z = 6
    z *= 2 # z = z * 2 と同じ
    print z

    w = 12
    w /= 3 # w = w / 3 と同じ
    print w

    x = 6
    x++ # x += 1 または x = x + 1 と同じ
    print x

    y = 6
    y-- # y -= 1 または y = y - 1 と同じ
    print y
}

scpt6_2.awk の実行結果は:

[cactus:~/code_awk/tuts]% ./scpt6_2.awk
8
2
12
4
7
5

awk の組み込み算術関数

awk は数値の計算のために, いくつか独自の組み込み算術関数を用意してくれている.

scpt6_3.awk

#!/usr/local/bin/gawk -f
# scpt6_3.awk

# Numeric Functions
# AWK has the following built-in arithmetic functions:
##################################################################################
# atan2(y, x)   Returns the arctangent of y/x in radians.
# cos(expr)     Returns the cosine of expr, which is in radians.
# exp(expr)     The exponential function.
# int(expr)     Truncates to integer.
# log(expr)     The natural logarithm function.
# rand()        Returns a random number N, between 0 and 1, such that 0 <= N < 1.
# sin(expr)     Returns the sine of expr, which is in radians.
# sqrt(expr)    The square root function.
# srand([expr]) Uses  expr  as  a  new seed for the random number generator.
# If no expr is provided, the time of day is used.
# The return value is the previous seed for the random number generator.
##################################################################################

BEGIN{
    print atan2(10, 2)
    print cos(10)
    print exp(10)
    print int(23.44)
    print int(-23.44)
    print rand()
    print sin(10)
    print sqrt(100)
    print sqrt(23)
    print srand()
}

scpt6_3.awk の実行結果は:

[cactus:~/code_awk/tuts]% ./scpt6_3.awk
1.3734
-0.839072
22026.5
23
-23
0.237788
-0.544021
10
4.79583
1